by Andrew Healy (KC-NE) and Scott Kacsmar (PIT-DEN)

It certainly seems like the NFL has never seen a year with as many injuries as 2015, and in particular, a year with as many important injuries to important players. And those injuries have defined the AFC playoff race much more than the playoff race in the NFC. Only two of the six AFC playoff teams started the same quarterback in all 16 games this season, but Kansas City and New England made up for it with plenty of injuries to stars at other positions. We don't know if Denver is making the right decision by going back to Peyton Manning at quarterback, in part because we don't know how healthy Manning truly is, and we don't know how much Ben Roethlisberger's shoulder injury will shut down the Pittsburgh passing game even if he plays. Beyond quarterback, we don't know what to expect from players with recent injuries (Jeremy Maclin, Spencer Ware) or what to expect from players returning from injury (Julian Edelman, Dont'a Hightower, DeMarcus Ware, and even though he did play last week, Justin Houston). Unfortunately for Pittsburgh, we do now know what to expect from the league's best wide receiver, Antonio Brown: nothing, thanks to a concussion that will keep him out of Sunday's game.

For those who may be unfamiliar with the Football Outsiders stats, they are explained at the bottom of the page. Scroll down or click this link. Game charting data appears courtesy of either ESPN Stats & Information or Sports Info Solutions.

Kansas City at New England

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At kickoff on Sunday, it will be 22 years to the day since the last time the Kansas City Chiefs won a divisional round playoff game and advanced to their lone AFC Championship Game since the merger. That day, the Chiefs lined up against a Houston Oilers steamroller that had won 11 games in a row after starting 1-4. Those Oilers finished the year first in weighted DVOA at 33.1% primarily on the backs of Buddy Ryan's blitz-crazy defense, which also ranked first in weighted DVOA. The Chiefs arrived in Houston as seven-point underdogs, looking like cannon fodder for the Oilers to easily dispatch before going to Buffalo to avenge the previous year's 35-3 collapse. But Ryan ran into the wrong quarterback. 37-year-old Joe Montana threw quickly to deal with the blitzes he knew were coming, torching single coverage again and again to long forgotten receivers Willie Davis, Keith Cash, and J.J. Birden. And long after it became clear that the blitzes weren't working, Ryan kept bringing them anyway, incapable of learning from his mistakes.

This Saturday, it's the Chiefs who enter on an 11-game winning streak, riding a dominant defense after starting the season 1-5. As with the 1993 Oilers, it's the matchups at coach and quarterback that stand in the way of the Chiefs' extending their win streak to 12. Like Ryan, Andy Reid is an innovator who has succeeded in multiple environments as a coach. His remarkable work this season is one of the main reasons that the Chiefs rebounded from the loss of Jamaal Charles to finish the season third in weighted offensive DVOA. Despite his strengths as a schemer and playcaller, nobody is taking Reid in the matchup with Bill Belichick when it comes to strategic in-game decisions on Saturday.

And like Montana blocking the path of the 1993 Oilers, 38-year-old Tom Brady stands in the way of this year's Chiefs. In a league driven even more by passing now than it was 22 years ago, the presence of Brady and Belichick combined with having to travel to Foxborough is enough to make the Chiefs five-point underdogs against the Patriots, but an unusually ambiguous injury situation clouds the outlook. Not only are the Chiefs missing Charles and left guard Ben Grubbs to season-ending injuries, they appear to be down Jeremy Maclin after an injury last week against the Texans, and it's unclear how much they can expect to get from All-Pro outside linebacker Justin Houston or his veteran bookend, Tamba Hali.

For the Patriots, the injury situation is infinitely more confusing. Rob Gronkowski may have gotten a knee injection on Thursday. Or maybe he didn't. Brady, Devin McCourty, Julian Edelman, Sebastian Vollmer, and Dont'a Hightower all seem likely to play, but none are completely healthy. Chandler Jones took a weekend trip that went terribly wrong. The Patriots seem decidedly unmachinelike as they enter the postseason, looking to grab their fifth Lombardi of the Bradichick era. After getting a huge boost from a mostly clean injury sheet last year, the Patriots entered the postseason as the highest-variance proposition in the playoff field based on their uncertain health situation. These Patriots have the biggest upside of any AFC team, but they're also holding on for dear life right now.

WHEN THE CHIEFS HAVE THE BALL

As Jamaal Charles took the cart ride into the tunnel in the second half of Week 5, he seemed to take the Chiefs' chances of having a decent offense with him. In Andy Reid's first two seasons in Kansas City, the Chiefs had finished 15th and 12th, respectively, in offensive DVOA with an average passing game and a top-five Charles-led rushing attack in both years. The last time the Chiefs had to play without Charles for an extended stretch, in 2011, the Chiefs had the second-worst rushing DVOA in the league. But that was before Reid took over and before Alex Smith arrived. What happened after Charles' injury showed how much the Chiefs' rushing success is due to their underappreciated head coach and quarterback.

From Week 6 on, the Chiefs fielded the third-most efficient offense in the league, and the league's best rushing attack. No successful offense this season was driven by the running game the way that the Chiefs were. Out of the league's top ten offenses, the Chiefs had the least efficient passing game (ranked 14th). Passing is so much more efficient than running that every NFL team had a higher passing DVOA than running DVOA this year. Even for the Chiefs, a pass produces slightly more value than a run, on average. But in contrast to most teams, the difference for the Chiefs is so close that they should balance running and passing roughly equally rather than using the run as a change of pace.

The Patriots rank similarly against the run (10th) and the pass (13th), so there's no obvious reason for Kansas City to change the run-pass balance because of opponent. What the Chiefs could consider doing is shifting even more to zone-read runs where Spencer Ware is the running back. Ware has been by far the Chiefs' most efficient back since Charles got hurt. Across his 72 regular-season carries, he compiled a DVOA of 25.8% that ranks fifth among backs who got at least 70 carries. Ware's advanced stat line is strikingly similar to Charles' (71 carries, 24.8% DVOA). Ware's efficiency far outstrips Charcandrick West's, who finished the year slightly above average at 3.0% DVOA (ranked 20th). The Chiefs appear to have made the decision to feature Ware more than West. Against Houston, Ware got 16 carries, posting a DVOA of 11.3% on those runs. West got eight carries and put up a DVOA of -12.1%.

Whether Ware or West is the back, the Chiefs have been most efficient this year running out of the shotgun, where their rushing DVOA was 26.3%, compared to 0.7% on other runs. While the Chiefs' variety in their run looks helps explain their success, zone-reads out of the shotgun have produced their most consistent yardage. Zone-reads also bring into play the potent threat that Alex Smith poses as a runner. Only Cam Newton, Russell Wilson, and Tyrod Taylor had more carries at the quarterback position this year than Smith. Not including scrambles, we have Smith with 72 runs for a career-high 509 yards. The Patriots defend shotgun runs relatively well (-10.3% DVOA, ranked 8th), but they struggled more in their two games against Taylor, the biggest running threat they faced at quarterback this season.

When the Chiefs run, they might want to lean left. Even though the Chiefs lost their best lineman in left guard Grubbs to a Week 7 injury, they haven't missed a beat with Jeff Allen stepping in at that spot. And the splits point towards previously maligned left tackle Eric Fisher having considerable success as a run blocker in his third year.

Chiefs Adjusted Line Yards By Direction
Left End	Left Tackle	Mid/Guard	Right Tackle	Right End
4.47 (5th)	5.08 (1st)	4.38 (2nd)	2.64 (30th)	2.40 (28th)

The Chiefs run 71 percent of the time up the middle or over a guard, but split the rest of their carries roughly evenly between the left (14 percent) and the right (15 percent). The differences in blocking efficiency are so big here that these splits are more than just a random fluke. With the Patriots roughly even in defensive efficiency on runs to the left and to the right, the Chiefs should look to call most of their outside runs to go to the left.

Overall, the Chiefs' line ranked fifth in adjusted line yards, but just 28th in adjusted sack rate. The high sack rate reflects Smith's cautiousness with the ball, but it also reflects the line's weaknesses in pass protection. It's this matchup of the Patriots' defensive line (7.8% adjusted sack rate, ranked second) against the Chiefs' pass protectors that presents the most danger for the Chiefs. This Patriots' defense bears little resemblance to the secondary-driven defense of last year that ranked 20th in adjusted sack rate. Chandler Jones, Jabaal Sheard, Jamie Collins, and Co. have swarmed better pass-protecting lines than this Chiefs unit.

Reid will certainly adapt by scheming to get the ball quickly out of Smith's hands. That has been the game plan for most of the season. The Chiefs threw deep (more than 15 yards in the air) just 64 times all season, 20 times fewer than any other team. But Belichick and defensive coordinator Matt Patricia will be preparing for the Chiefs to follow their usual cautious diet of short throws. With Maclin (the target on 26 of those downfield throws) out this weekend, the Patriots are likely to be ready to pounce on those short throws.

Football fortune often favors the bold. (Just ask Nick Saban). Reid should toss in more deep shots than he usually does, hoping to catch the Patriots expecting that he won't. It's a great David strategy for an underdog that should be looking to take chances. And even though the Chiefs haven't used their best remaining receiving threat on deep throws very much, Travis Kelce has the necessary skill set. Almost Gronk-sized, Kelce is in the running to be the fastest tight end in the league. By only targeting Kelce eight times on deep throws during the regular season, the Chiefs didn't take their high-performance car for a real spin. Against Houston, they made a small move in that direction, hitting Kelce on one deep target that went for 48 yards and a couple other throws that went more than 10 yards in the air.

During the regular season, the Patriots were just average against tight ends, ranking 15th in DVOA, suggesting the matchup with Kelce would favor the Chiefs. Part of that was a low target total, however, as the Patriots gave up the third-fewest receptions to tight ends. New England has a variety of ways they could cover Kelce, including using safety Patrick Chung or linebacker Jamie Collins in coverage. In Week 5, Devin McCourty helped limit Jason Witten to just 33 yards on six targets. McCourty might be the best option -- if he was healthy. With McCourty at less than 100 percent, the Patriots could look to have multiple defenders involved on most plays. Going that way could leave an opportunity to hit rookie Chris Conley on deep throws. Conley didn't put up enough college production to get a high Playmaker Score, but he has the physical tools (4.35 40-yard dash, third-highest vertical leap at the combine since 2003) to be a deep threat. Smith hit half his small sample of deep throws both to Conley (10 targets, 91.0% DVOA) and Kelce (eight targets, 91.3% DVOA).

In coverage, when throwing short, Smith should look to go after anyone but Malcolm Butler. Last year's Super Bowl hero had the Patriots' best charting stats. Per Sports Info Solutions, Butler ranked 15th among corners with a 60 percent success rate. Butler's aggressiveness, however, made him vulnerable to the big play. He gave up 8.5 yards per pass, the same as Logan Ryan. Some of those big plays came against receivers such as Antonio Brown and Odell Beckham. Without Maclin, the Chiefs receivers are a Vince Wilfork-sized step down in difficulty.

WHEN THE PATRIOTS HAVE THE BALL

Over the last decade, nothing has been more predictable than the Patriots rolling into January with one of the NFL's most potent offenses. From 2007-2014, the Patriots never ranked lower than third in weighted offensive DVOA, and that includes one year with Matt Cassel at quarterback.

Before the season and through the first half of the year, the run appeared likely to continue. But then the Patriots' offense fell off a cliff. They ranked just 14th in offensive DVOA over the last eight games of the season, finishing tenth in weighted offense at 8.4%. Statistically, this season ended up playing out somewhat like 2014, but in reverse.

Breaking Down New England's Offensive Efficiency
Year	Games 1-8	Rk	Games 9-16	Rk
2015	24.1%	2	5.6%	14
2014	8.8%	14	18.0%	4

Rather than starting the season with an offensive line in flux and a quarterback under siege, this year the Patriots ended it that way. As unpromising as that sounds, last season also shows just how fast the Patriots can return to offensive machine mode, as it was just those first four weeks when the offense struggled. In games 5 to 8 last season, the four games after the 41-14 stomping in Kansas City, the Patriots ranked second in DVOA (29.5%). The big step last year was settling on an offensive line after that debacle. This year, the Patriots' chances again hinge on finding some stability on the line. Sebastian Vollmer returns this week, but the prospects look dicier this year with Marcus Cannon still likely to be playing right tackle. The line doesn't need to be great; it wasn't last year. But what they have gotten recently is not going to be good enough against a Chiefs defense that ranks fourth in adjusted sack rate.

Brady's decisiveness provides a huge advantage in avoiding sacks. He is by far the biggest reason that the Patriots ranked in the top ten in adjusted sack rate allowed every year from 2004 to 2014, except 2008. (The one year Matt Cassel was behind center, the Patriots ranked 26th in adjusted sack rate.) This year, even Brady couldn't keep the Patriots in the top half of the league, as the Patriots finished 18th.

Pass protection would loom as an even larger problem if Tamba Hali or, more importantly, Justin Houston were fully healthy. Hali played just 29 percent of the snaps in the wild-card win against the Texans, but was already on the downside. Houston led the league with 22.0 sacks last year. This year, Houston missed five full games with injuries and was held to 7.5 sacks -- which still led the team. Pass rushing has come from all angles on this Chiefs defense this season, including the interior line from Dontari Poe and Jaye Howard.

The Chiefs' supplement their pressure with aggressive coverage that can shut down shorter routes. Kansas City ranked third in DVOA against short passes (pass that traveled 15 yards or less beyond the line of scrimmage). In Week 10, against a Denver team that had little threat of going deep, the Chiefs relentlessly attacked the shorter routes and humiliated Peyton Manning (5-for-20 for 35 yards, 0 TD, 4 INT) on the day he broke the all-time passing yardage record.

Of course, the Patriots have used short routes to beat teams that stop short routes before. Last year, Seattle's defense entered the Super Bowl ranked third in DVOA against short passes. That didn't stop the Patriots from carving the Seahawks up with short passes, particularly after Tharold Simon replaced the injured Jeremy Lane at corner. In coverage, the Chiefs' usually play a similar style to Seattle, a Cover-3 scheme that uses two bigger cornerbacks -- 6-foot-2 Sean Smith on the left and 6-foot-0 rookie Marcus Peters on the right -- who mostly stick to a side. Julian Edelman has the sort of quickness that matches up better against Smith, in particular, than would more typical No. 1 receivers. If Edelman is healthy, all of Kansas City's success on shorter routes against other teams might not mean that much.

While the Patriots pose a different threat on shorter throws, the Chiefs' relative weakness has been on deeper throws (17.1% DVOA, ranked 16th), particularly to Smith's side of the field. On throws to the deep left, the Chiefs' defensive DVOA is 43.8%. The Patriots could use route combinations to draw Smith forward and then throw downfield behind him.

In one crucial sense, these Chiefs match up better in coverage against the Patriots than did last year's Seahawks. While Seattle ranked just 18th in coverage against opposing tight ends, the Chiefs rank second with a DVOA of -36.4%. The Chiefs haven't faced a tight end nearly as good as Gronkowski in compiling those numbers, but last season they limited a still-recovering Gronk to just two catches on three targets in limited action in Week 4. The better matchup could be Edelman's, further emphasizing how much the Patriots' offense may depend on his effectiveness in his first game back from his foot injury. The Chiefs rank only 21st (7.5% DVOA) against opponents' No. 1 receivers, many of whom matched up not as well as Edelman against the Chiefs' bigger corners. The matchup is certainly winnable for the Chiefs. Against a Patriots team at its nadir last season, they held Edelman to four catches for just 23 yards. The Patriots particularly struggled on throws over the middle to Edelman in that game, where safety Husain Abdullah also helped in coverage. The Chiefs, like the Patriots, >often use extra safeties rather than corners in nickel or dime coverage to supplement their primary safeties (Eric Berry and Ron Parker). If the Chiefs scheme to focus heavily on their matchup weakness with Edelman, expect adjustments to direct throws more to Danny Amendola and Gronkowski.

Unlike the Chiefs, the Patriots have not run effectively this season. That was also true last year, and it didn't stop them from having one playoff game where they pounded the rock. Against the Colts' No. 19 run defense, the Patriots ran 40 times. In the other two games against the Ravens (No. 5 in run defense) and Seahawks (No. 2), the Patriots ran 34 times combined. With the Chiefs' No. 11 run defense falling in the middle, the outlook is for the Patriots to test the waters with some Steven Jackson carries early. If they fail, the Patriots are uniquely adept at changing course and paying no tribute to the gods of run-pass balance. Last year against the Ravens, no Patriots' running back got a carry in the second half.

SPECIAL TEAMS

In the midst of the unpredictable chaos of special teams, the Patriots and Chiefs stand out as beacons of consistency. The Patriots have ranked in the top ten on special teams nine of the last ten years, finishing fifth this year despite the Week 13 debacle against the Eagles. Stephen Gostkowski had his best year yet by total value added accounting for game situation. The Patriots led the league with 14.1 points of value added on field goals and extra points. Gostkowski sometimes got too much credit in earlier years for a success rate inflated by easier kicks than most other kickers took. Not lately -- this was the third consecutive year that Gostkowski added at least ten points of value on field goals and extra points. The Patriots' success on kickoffs goes back even longer. For the fifth straight year, the kickoff unit added at least eight points of value.

For all of Gostkowski's success, he's got nothing on Chiefs special teams coach Dave Toub. Over his last ten years as a special teams' coach (2006-2012 with the Bears and 2013-2015 with the Chiefs), Toub's units have finished at No. 1 five times and never lower than their No. 7 ranking this year. When Toub left the Bears, they ranked 11th and 25th in the two years following his departure. In the year before he arrived in Kansas City, the Chiefs ranked 22nd. Devin Hester certainly helped in Chicago, but Toub has been guaranteeing elite special teams units for a decade. Just watch the practically perfect blocking on Knile Davis' game-opening touchdown return last week to appreciate Toub's value. A special teams touchdown on Saturday would obviously be an enormous boost for the Chiefs, but it's not likely against a team as disciplined as the Patriots.

But Toub's value extends beyond returns. The Chiefs' punt coverage unit was slightly above average in the first eight years of punter Dustin Colquitt's career. In the last two, the Chiefs have added more than ten points of value on punts, this year leading the league with 16.2 points. Twice against the Texans, Colquitt got a punt to land on the 5-yard line with the spin needed to pull it back. The Chiefs' coverage unit downed another punt on the 1-yard line. Under Toub, somehow that annoying result where the coverage guy carries a ball into the end zone didn't happen when it seemed likely on that play.

OUTLOOK

Saturday's game is about as easy to predict as the winning Powerball numbers. Almost all of the Patriots' most important players are dealing with an injury, but it's possible that most or all could be at close to 100 percent. The Chiefs don't know what they're going to get from their best pass rusher, or if their passing game has life without their leading receiver.

If Kansas City can get to the red zone, they have the league's second-best red zone offense and top-ranked red zone rushing offense. But getting there presents a problem. Not even the Chiefs can win with the run alone, and their leaky line faces a serious matchup problem against the league's second-best pass rushing unit by adjusted sack rate. When they do get close, Reid needs to kick less and go for it more than he has in the past. If he faces fourth-and-short in opposing territory early on, Reid needs to ride his league-best rushing attack. In 1993, Buddy Ryan's biggest mistake was not adapting his strategy to the opponent, as he continued to go balls-to-the-wall even when the situation called for him to be less aggressive. As the underdog against the Patriots, Andy Reid needs to adapt to by being more balls-to-the-wall on fourth down.

Brady and Belichick might have hoped for any matchup other than this one, where they have to face a defense that swarms short passes, stifles tight ends, and harasses quarterbacks with questionable offensive lines. But while the Patriots' offense has sputtered in recent weeks, it has chugged along under almost all circumstances in a much larger sample. With Vollmer and Edelman coming back, the Patriots' offense has the better hopes of squeezing some points out of a difficult matchup.

Pittsburgh at Denver

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A decade ago this week, Pittsburgh reveled in its underdog status as a sixth seed heading into Indianapolis in a season when Peyton Manning finally "had a defense." Joey Porter was in the news with his claims that the Colts were a soft team that wanted to trick you instead of lining up to play smashmouth football. The Steelers opened up a quick 14-0 lead and Porter was redeemed with a big performance in Pittsburgh's upset win after one of the wildest endings in playoff history. It was an ending the Steelers almost recreated in Cincinnati last week, barely getting by the Bengals to make it this far. Even Porter made himself relevant on the field, albeit as an assistant coach.

Much like the 2005 Steelers, the 2015 team is better than its season-long statistics suggest due to the time Ben Roethlisberger missed with multiple injuries. However, this year's defense is not on par with that championship lineup, and this team is not nearly as balanced as the 2005 team, an atypical sixth seed that was a legitimately great team. The 2015 Steelers are much more reliant on Roethlisberger throwing to his talented receiving corps, led by Antonio Brown. Pittsburgh stands little chance of winning with those two players sidelined by injury. Heading into Friday, we still are not sure what to expect from Roethlisberger, who has been very limited in practice since he suffered an AC sprain and two torn ligaments in his throwing shoulder. Brown was ruled out for Sunday with his concussion, a major blow to this prolific passing game.

Uncertain offense has been on the menu all year for Denver. Even if the Steelers had not already put a muzzle on him, Porter would not have anything controversial to say about this 2015 version of the Manning-led offense, because it is unrecognizable from the well-oiled machines of yesteryear. Manning is going to make his first start since Week 10 against the Chiefs, inarguably the least effective game of his career. Manning may have wanted a defense to help him a decade ago, but at this stage of his career he needs his defense to play at a high level. While in the past one would suggest a bye week hurts Manning's rhythm, this time it was essential to getting him as healthy as possible for this matchup. Given the other defenses in the AFC playoffs, Pittsburgh is the most favorable draw.

It really is a shame injuries are likely to impact the quality of this game, because there may not be a better matchup this season than Pittsburgh's offense against Denver's defense. You must expect it will look way different from this year's 34-27 game in Week 15, won by the Steelers in Pittsburgh. We will make many references to Pittsburgh's 17-point comeback that beat Denver just four weeks ago, but only because that is such a recent matchup in this series. Prior to that game, these teams last met in the 2012 season opener, won 31-19 by Denver in Manning's debut with the team. Is this the end of his career should Denver lose? The Steelers have a tough task ahead of them. Unlike a decade ago, the underdog label really fits this week, even if Denver is not a juggernaut this year.

WHEN THE STEELERS HAVE THE BALL

Ben Roethlisberger is one tough player. In an era of tactical silence on injuries, he'll break the news that he has torn ligaments in addition to the previously reported AC sprain in his shoulder. His infatuation with talking about his injuries goes back to his rookie season when he talked about having broken toes in the AFC Championship Game loss, a story of which then-coach Bill Cowher would have no part. Has Roethlisberger exaggerated his injuries in the past? Sure, which is why some in Denver might be thinking this is the greatest long con ever attempted and it will be bombs away on Sunday. Frankly, it really is a miracle Roethlisberger's season is still going after setting a record for mileage on the cart.

Seriously, how is Ben Roethlisberger's season even still going? 3 cart rides & left a 4th game concussed pic.twitter.com/mqkxhRxrPb

— Scott Kacsmar (@FO_ScottKacsmar) January 15, 2016

No one can question his toughness, and the praise for it seems to be a fetish for Roethlisberger in the way those characters got off on car crashes in David Cronenberg's 1996 film Crash. This would be the ultimate high, to beat the league's best defense again in the playoffs with a barely functioning right arm. Or is it healthy enough to play Roethlisberger's usual brand of offense? We won't really know until the game kicks off on Sunday, but for the purposes of getting this preview out in a timely manner, we are going to assume a limited Roethlisberger gets the start. If Landry Jones has to start, you can forget about this game being very competitive or watchable. He is not ready for this stage, especially without Brown to move the chains.

This would be Roethlisberger's third playoff start in Denver. The first was one of the finest games in his career a decade ago, while the last is a black mark on his resume: an ineffective performance on a high ankle sprain in the 2011 season where he lost to a deity in overtime. Sunday's performance might be able to fall somewhere in the middle. Even a healthy Roethlisberger needed the largest comeback of his career (17 points) to beat Denver at home in Week 15. No offense outside of Arizona is really built to attack the Broncos the way Pittsburgh was this year. Roethlisberger is the only 300-yard passer Denver has allowed, and the Steelers were the only team to crack 30 points on the Broncos. They did this with a pass-happy attack where Roethlisberger had 58 dropbacks to just 14 handoffs for 26 yards. That sounds like a recipe for a road loss and a bad idea for a quarterback with a shoulder injury.

The problem is Pittsburgh has few options other than to try throwing often. Le'Veon Bell is not walking down that tunnel. DeAngelo Williams, the team's leading rusher this season, is also out with an ankle injury. While Fitzgerald Toussaint and Jordan Todman were very impressive in Cincinnati last week behind this talented offensive line, it is unlikely Pittsburgh will make much hay against Denver's run defense. The Broncos rank first in second level yards and second in open-field yards, meaning running backs do very little after getting 5 yards beyond the line of scrimmage. Seven teams cracked 100 rushing yards against Denver this year, but only two of those teams (Kansas City in Week 2 and San Diego in Week 17) did it without the aid of the quarterback's rushing. Roethlisberger ran six times this season for 38 yards, including two quarterback sneaks. He is not going to be a running threat, especially this week.

The backs may not do much in the receiving game either, with the Broncos ranking second in DVOA in coverage against running backs. Yes, Charcandrick West (80 yards) and Brandon Bolden (63 yards) had long touchdown catches against Denver this year, but those were also on throws that traveled 15 yards from the line of scrimmage to take advantage of holes in downfield coverage. On the season, Roethlisberger was 0-for-3 with one bad interception on throws to running backs more than 7 yards down the field. Screens and checkdowns to running backs are his friends here, but the Broncos defend those well. Pittsburgh may need to get creative again with a trick play to get the ball in the hands of Martavis Bryant like his 44-yard run last week.

Pittsburgh's passing game revolves around its three wide receivers with Markus Wheaton improving this year, but Brown was the main attraction and the most consistent wideout in the NFL. In Week 15, Brown was incredible, with 16 catches on 18 targets for 189 yards and two touchdowns, the first scores allowed by cornerback Chris Harris in 35 games. Harris will likely see a lot of Wheaton this week, and that is a much more favorable matchup for the cornerback. The bigger Aqib Talib will cover Bryant, who can score from anywhere on the field, but his routes are not varied enough yet to fill the No. 1 wide receiver role. This offense thrives on Roethlisberger throwing vertical passes.

Denver still has three good cornerbacks, but Pittsburgh can no longer counter with three good wide receivers. Bradley Roby may see his share of Darrius Heyward-Bey, who caught 21-of-39 targets this year (good for his standards), but is clearly a major downgrade for the offense. In Week 15, Pittsburgh had six plays gain at least 16 yards, but Brown had five of them and Williams had the other. Denver did not allow a gain longer than 23 yards.

In fact, Pittsburgh's approach to Denver went against the norm this year. Roethlisberger averaged 7.7 air yards per attempt, his third-lowest average in a 2015 game. He was only 2-of-5 for 39 yards and an interception on deep passes that traveled more than 15 yards beyond the line of scrimmage. That goes against the season numbers for Denver, which ranks first against short passes and seventh against deep passes. An area of weakness for Denver has been passes thrown to the deep right, the type of throws on which Roethlisberger finished with the third-most DYAR (376) this season.

Now we wait to see if Roethlisberger can still make those deep throws this week. It is hard to imagine he would hold back on purpose in a playoff game with the season on the line. Roethlisberger threw eight passes on Pittsburgh's game-winning drive in Cincinnati, and seven of them traveled less than 5 yards down the field. His one longer attempt was the high pass to Brown that led to the receiver's concussion. That ball had good zip, but was not accurate. That cannot be the case on Sunday.

The Steelers may also be challenged to throw deep this week due to Denver having its safeties back. T.J. Ward, Darian Stewart, and Omar Bolden were all inactive in Week 15, leaving David Bruton to play 77 snaps despite breaking his leg in the first quarter. Josh Bush played 61 snaps and intercepted Roethlisberger, who had his highest interception rate since 2006 this year. Shiloh Keo played 87 snaps on defense this season and 37 were in this game. Denver will feel a lot more comfortable with its normal safeties on the field. The injury report in general looks good with DeMarcus Ware and Brandon Marshall likely to start despite some recent injuries. Von Miller should be fine to rush the quarterback after mozzarella sticks caused a mid-week illness (no, seriously). The toy box is full for defensive coordinator Wade Phillips.

Roethlisberger will need all the protection he can get this week, but this is an interesting matchup. According to ESPN, the Broncos get pressure on quarterbacks at a league-high rate of 34.7 percent. Roethlisberger is the least-pressured quarterback at 19.9 percent, which sounds unfathomable considering the way he has played in his career, but he has adapted his playing style as he's gotten older. He still can shake off a sack and make something happen. Roethlisberger's 33.1 QBR while pressured ranked sixth in 2015. Oddly enough, Denver's defense only has six takeaways at home compared to 21 on the road.

The red zone is one of the few areas where the Broncos defense is nothing special, ranked 13th in DVOA, 30th against the run, and 15th in points per drive. Pittsburgh's offense feels like it settles for a lot of field goals, yet it still ranks seventh in points per red zone trip. There is a simple explanation for this. While the Steelers have attempted a league-high 42 field goals, they also are tied with Baltimore for the most field-goal attempts outside the 20-yard line (23). In the red zone, this offense has relied heavily on Brown and Williams, which is obviously a problem this week. Brown had 74 of the team's 75 receiving DYAR in the red zone. Williams and Bell had 133 of the team's 127 rushing DYAR in the red zone, which means the other players contributed minus-7 DYAR. The onus is likely to fall on Bryant and Heath Miller to pick up the slack here.

Denver's aggressive play on defense has likely been a net positive for Phillips' unit, but at times it does hurt the team in the form of penalties. Denver was the most penalized defense (63 accepted for league-high 628 yards) in 2015. Sometimes that can be for something minor like offsides, for which Denver was flagged 16 times (12 accepted), tied with Miami for the most in the NFL. Denver was flagged above the league average for the more serious 15-yard penalties such as unnecessary roughness (10 flags), roughing the passer (six), and unsportsmanlike conduct (four). One of the season's rare ejections happened when Ward attempted a punch at Jeremy Maclin in Week 10. That was just one week after Talib was suspended for poking Dwayne Allen in the eye, which cost the Broncos a chance to get the ball back in the final minutes in the Indianapolis loss.

I bring up the penalties for two reasons. First, some Broncos have mentioned taking legal shots at Roethlisberger's shoulder -- driving him into the ground -- if the opportunity presents itself. That may not go over well, as the NFL will not want a repeat of last week's Pittsburgh game with the Bengals. We may see some of that animosity given the Cody Wallace situation. In Week 15, Pittsburgh's center delivered a major cheap shot to Bruton after the whistle. Some thought a suspension was warranted, and the Broncos have not forgotten this hit. Stewart has said he will cut block Wallace if he comes at him this week.

WHEN THE BRONCOS HAVE THE BALL

For a change, postseason offensive expectations are not very high for Peyton Manning after the 39-year-old paired up with Gary Kubiak and produced his worst season. You name a stat, and the 2015 Manning probably did his worst ever, or at least since his rookie season. After 15 straight years of ranking in the top eight in DVOA, he finished 36th out of 37 passers this season. While he still led some timely drives in the fourth quarter and overtime (Denver led the league with six 4QC/GWD wins; Manning had three) his other situational football (third down and red zone plays) was not up to par. He threw an interception in every start, and his 17 picks in ten games came in every way imaginable, from throws that looked physically weak to tipped balls to predetermined passes, but the most alarming were some of the baffling mental decisions. Maybe that was adjusting to Kubiak's offense, but five multi-interception games in Weeks 4 to 10 were way too many.

It probably does not make much sense to consider the 2015 Broncos a Manning team due to lost time and since the offense is so far behind the defense, but he is still the starter and will have the pressure to win in perhaps his final season. In the past, his teams have usually struggled with the same few opponents on an annual basis. In Indianapolis, the enemies were New England (always a tough out) and San Diego. In Denver, it should be acknowledged that Baltimore, Seattle, and Indianapolis have been successful against this team, even if only in small sample sizes. With Pittsburgh, the history is just not there. Manning has only played the Steelers five times in his career, his fewest starts against any AFC opponent not named the Colts (against whom he already has four starts).

The Steelers are the best matchup Manning could have asked for this week, because this is a secondary that tends to allow big cushions, blow coverages, and whiff on tackles. By picking up the pace, Manning could potentially catch the Steelers in some bad coverages, though this is not the no-huddle offense he is used to running.

Whether it is Manning or Brock Osweiler at quarterback, the 2015 Broncos have been a subpar offense, with issues ranging from a bad offensive line to an inconsistent running game to a shallow receiving corps that struggles with drops and producing yards after the catch. If Manning plays like he did against the Chiefs in Week 10, they will not beat anybody, but it is safe to assume that was an injury-affected outcome. His two best games this year were the ones right before that. Manning has had time to let his plantar fascia heal, and he looked healthy in his relief performance in Week 17 against San Diego. Granted, nine pass attempts against a San Diego defense missing its best players does not tell us much, but at least he looked very much in control of the offense and even handed the ball off from under center several times.

We could go into much more detail on the Manning-Kubiak split offense this week, but I frankly have low expectations for this game given Pittsburgh's injuries. Denver, favored by a touchdown, should win, so let's bank on covering more of the specifics in next week's preview and stick with the matchup-specific stats for this game. That's a risky decision to be sure, but it does not seem to make sense to talk about why Denver's offense has been so unproductive before a game where it may only need to score 23 points to win. This is a defense-led team.

The offensive line has been a major problem, as anyone following Denver knows well. Denver lost two left tackles to injury and benched Evan Mathis for rookie Max Garcia, and right tackle Michael Schofield is still leading prison breaks to his quarterbacks. Our own Ben Muth recently called Schofield the "worst player I've ever seen start multiple games." Schofield was replaced by Tyler Polumbus (who has had his own career struggles) in Week 17, though Kubiak has reportedly said both will play this week. Either way, it is a problem as Manning is not used to this amount of pressure, nearly double his usual rate. The following data comes from ESPN, though 2015 is subject to change after we clean up this year's charting. We also only have QBR under pressure instead of DVOA for 2015 at this time.

Peyton Manning: Under Pressure
Season	Team	Coach	Pressure Pct.	Rk	DVOA w/Pressure Rk	Sack%	Rk
2010	IND	Jim Caldwell	13.8%	1	8	2.3%	1
2012	DEN	John Fox	13.3%	1	14	3.5%	2
2013	DEN	John Fox	14.8%	1	10	2.7%	1
2014	DEN	John Fox	13.1%	1	27	2.8%	1
2015	DEN	Gary Kubiak	25.4%	16	18 (QBR)	4.6%	8

Pittsburgh's defense was only 27th in pressure rate (25.1 percent), so getting there has not been easy. When they did get pressure, though, they allowed a league-low 3.0 QBR, so this could be a problem for the passing game despite Manning's quick release. Defenses liked to blitz Manning this year, coming at him on 35.3 percent of plays (seventh-highest) compared to just 23.5 percent for the inexperienced Osweiler (fourth-lowest). The Steelers are totally reliant on takeaways (seventh per drive) and red zone stops (second per drive) as they only rank 26th in punts per drive. Half of Pittsburgh's 14 takeaways on the road came in Cincinnati over the last month.

Manning should take advantage of Pittsburgh's cushions with play-action passes on first down -- the Steelers rank 24th against first-down passes, while Denver's offense ranks 13th. We know Kubiak will want a strong running game to support Manning, but he cannot keep the offense in second-and-long situations where Denver ranked 31st this season. C.J. Anderson only had four carries in Week 15, but his ability to break tackles for big plays makes him likely to see more time in this one, along with Ronnie Hillman. The Denver running game has been very inconsistent and matchup-based, topping 100 yards in nine contests and failing to crack 70 yards in the other seven games. While some were quick to credit Osweiler for improving the running game, most of Denver's productive games have come with Manning, including four of the top six in yards and five of the top eight in DVOA. Look for Denver to try running off tackle where the Steelers ranked 25th on defense.

Don't expect much from tight end Owen Daniels, as his current level of athleticism is not much of a match for linebackers Ryan Shazier and Lawrence Timmons. Manning will rely heavily on Demaryius Thomas and Emmanuel Sanders, who both have good matchups and some big chips on their shoulders this week. Sanders already had a great game in Pittsburgh, with 181 yards against his former team in Week 15. Thomas is expected to play in front of his mother, now out of prison, for the first time. Think he'll have something to prove after the criticism for his dropped passes this year?

Pittsburgh should play tight man coverage, as that has always been the best way to disrupt Manning's timing-based passing game, but this secondary may not be capable of keeping up with those two receivers. William Gay still loses awareness on the field too often, and Antwon Blake has been a liability in coverage. He was pulled for most of the second half in Week 15, which may have had something to do with Denver getting shut out. However, Blake played most of last week's game over Ross Cockrell, so who knows what Mike Tomlin will do there? Brandon Boykin has been a charting favorite as a slot corner over the years, but this offense is not as slot oriented with the lack of a third receiving threat.

You can definitely throw deep (16-plus yards beyond the line of scrimmage) on Pittsburgh, which ranked 26th against such passes, but will Manning be able to hit those throws? He was 26-of-75 this year for a 34.7 percent completion rate, well down from his 47.0 percent rate in 2014. He usually overthrows these passes now, but a few early attempts should at least back up the Steelers and open up the underneath routes.

Pittsburgh allowed six 300-yard passers this year, and Osweiler barely missed being the seventh at 296 yards. This defense leaves a lot of plays open on the field, so Manning just has to play a smart game and not try to force too much, with the expectation that his defense will do its job.

SPECIAL TEAMS

We'll see if the Mile High altitude does anything for these two mediocre special teams units. Interestingly enough, Denver's special teams gained the most weather-adjusted field position value (9.1 points) this year, while the Steelers were 32nd (minus-6.7 points).

Chris Boswell, fresh off a game-winning field goal in Cincinnati, has been an excellent find for the kicker-needy Steelers. He has made 33 of his first 36 field goals, including 11-of-14 from 40-plus yards. The criticism for him comes on kickoffs, where he has only gotten a touchback 35.1 percent of the time, the lowest rate in the league. Brandon McManus is at 67.9 percent on touchbacks, the fifth-best rate in 2015. Touchbacks should be helpful here. In Week 15, Pittsburgh's four touchdown drives were 21, 58, 60, and 37 yards in length. Roethlisberger was unable to drive the long fields in that game. McManus has been a much improved kicker this season, though he had one of the ugliest misses you will ever see from 45 yards out with a chance to beat Cincinnati in regulation in Week 16. The last thing Manning wants to see is another "idiot kicker" costing his team a playoff game. Anything over 40 yards in crunch time for either of these young kickers could be an adventure on Sunday.

Neither return unit is anything special. Antonio Brown was the only real threat on punt returns. After the Jacoby Jones debacle, the Steelers are using Wheaton as a kick returner. Sanders has returned most of Denver's punts, but for a paltry 6.1 average. Safety Omar Bolden has missed seven games this season, but look for him to take over return duties on Sunday as he is (allegedly) healthy again. He had a big 83-yard punt return touchdown before halftime in Indianapolis earlier this season and could be the player to break a return in this game.

Gun to my head, I could not have told you the full name of Pittsburgh's punter this season. Maybe it's this RedZone era of switching to another game on punts, or the fact that the Steelers average the fewest punts per drive (.326) in 2015, but I blanked on Jordan Berry despite watching all 17 games. He has had a solid year with the Steelers, ranking 13th in gross punt value, and third at placing punts inside the 20 (47.5 percent). By comparison, Britton Colquitt's metrics are not as flashy, but his net average is a little better; hence Denver's punting is ranked a little higher than Pittsburgh's. But this is the most evenly matched part of this game, regardless of health for a change.

OUTLOOK

Except for Green Bay, every Denver opponent this season can say they beat the Broncos or almost beat them. The Broncos were 10-3 in close games. Pittsburgh, even in a wounded state, brings enough on both sides of the ball to keep this a competitive game. If Roethlisberger is healthier than he's letting on and the Broncos lose the turnover battle, the Steelers could win this one. Prior to Friday, Vegas seemed to like a 23-16 Denver win, which sounds totally logical -- but we know the playoffs can be anything but logical, especially when a Manning-led team is involved. Since winning Super Bowl XLI, Manning is 4-7 in the playoffs, having lost five fourth-quarter leads. The only two losses where he did not have a fourth-quarter lead were Denver's last two playoff outings: the Seattle blowout in Super Bowl XLVIII and last year's funeral march against Indianapolis.

Pittsburgh's game plan should actually try to resemble the one they used 10 years ago to take down the Colts and Broncos on the road. Roethlisberger must throw early and effectively to build a lead that will allow the defense to pressure Manning and force mistakes. The most likely path to a Denver loss is for the defense to have another off day, with the maligned offense unable to pick up the slack. The only problem is that leaves Pittsburgh with few options other than to be a successful passing offense -- which outside of that long con, just may not be reasonable with the health of Roethlisberger and absence of Brown. The top seed brings more advantages than just home-field advantage. Denver got to rest last week, while the Steelers suffered some unfortunate injuries that could be the difference in this rematch.

Of course, I warned last year that Manning's highest ranked regular-season defenses are 0-5 in the playoffs, as he made his best runs with his lesser defenses stepping up, but 2015 sure has felt different. It took 18 years, but Manning may have figured out that the way to get his defense playing at a high level was to play so inefficiently that it became a necessity. He can ride this defense to the Super Bowl finish he wants, where one good game will make people forget about the struggles of the last year. Now that would be quite the long con.

STATS EXPLAINED

DVOA (Defense-adjusted Value Over Average) breaks down each play of the season and compares it to the NFL average based on situation and opponent. You'll find it explained further here. Since DVOA measures ability to score, a negative DVOA indicates a better defense and worse offense, and a positive DVOA indicates a better offense and worse defense.

Team DVOA numbers incorporate all plays; since passing is generally more efficient than rushing, the average for passing is actually above 0% while the average for rushing is below 0%.

SPECIAL TEAMS numbers are different; they represent value in points of extra field position gained compared to NFL average. Field goal rating represents points scored compared to average kicker at same distances. All special teams numbers are adjusted by weather and altitude; the total is then translated into DVOA so it can be compared to offense and defense. Those numbers are explained here.

Each team is listed with DVOA for offense and defense, total along with rush and pass, and rank among the 32 teams in parentheses. (If the DVOA values are difficult to understand, it is easy to just look at the ranks.) We also list red zone DVOA and WEIGHTED DVOA (WEI DVOA), which is based on a formula which drops the value of games early in the season to get a better idea of how teams are playing now (explained here).

Each team also gets a chart showing their performance this year, game-by-game, according to total DVOA. In addition to a line showing each game, another line shows the team's trend for the season, using a rolling average of the last five games. Note that even though the chart appears in the section for when each team has the ball, it represents total performance, not just offense.