Best Cornerback Stats, 2015

by Carl Yedor

With Football Outsiders Almanac 2016 nearly ready for release, let's continue our look at some of our 2015 charting statistics with a discussion of the cornerbacks who did best in our charting metrics last season. (Later this week, we'll flip that around and look at players who ranked at the bottom.)

First, a reminder about how we changed our charting in 2015. In the past, our charting came from a combination of ESPN Stats & Info data and volunteer charting. In 2015, instead of volunteers, we partnered with Sports Info Solutions to do the portions of our charting that don't come from ESPN. That includes charting of pass coverage, and all the metrics below.

The main statistics we will be looking at today, adjusted for the quality of the opposing receiver:

• Yards per pass, the average yards allowed by the corner when targeted.
• Success rate, the percentage of targets where the corner prevented a successful gain (45 percent of needed yards on first down, 60 percent on second down, and 100 percent on third or fourth down).
• Estimated target rate, the percentage of possible targets with the corner on the field where the corner was targeted in pass coverage by the opposing offense.

We will be looking at plays where the cornerback was the primary defender in coverage, leaving out a few types of plays that do not properly reflect a cornerback's ability. These omitted plays include screens, balls tipped at the line or thrown away, Hail Marys, and plays where the quarterback was hit while throwing the ball. Defensive pass interference is included, but we ignore other defensive penalties that occur away from the pass. The "possible targets" from estimated target rate leave out the aforementioned omitted plays in addition to passes that were marked as "uncovered" or "blown coverage." However, if a play was marked as "hole in zone," the pass play was included.

Cornerback statistics are traditionally very volatile from year to year, and the best cornerbacks will often have worse results than expected because quarterbacks will be unlikely to target them unless they have already made a mistake. Seventy-five players met the benchmark of either starting eight games or facing 50 passes to be included in the list. It is important to note that with the number of players ranked, the difference between ranking 50th and 60th is not all that large, and therefore is not necessarily an indicator of a huge gap in talent.

We did change the way we did adjustments this year, in an attempt to partially solve the past problem where nickelbacks often ranked much higher than expected in these metrics. In the past, adjustments for offensive Team X were done by comparing Team X's No. 1 receiver to all No. 1 receivers, Team X's No. 2 receiver to all No. 2 receivers, and Team X's other receivers to all "other" receivers. In 2015, we adjusted instead by comparing Team X's No. 1 receiver to ALL wide receivers around the league. We hope this does a little bit more to penalize cornerbacks who cover nothing but slot receivers and boost the adjustments for cornerbacks who primarily cover No. 1 receivers.

First, we will look at best players by adjusted yards per pass allowed.

Leading all cornerbacks in 2015 was Patrick Peterson in Arizona at 4.4 yards per pass. Peterson had a truly dominant season for the Cardinals, as he also finished first in adjusted success rate. He was only the third cornerback to finish No. 1 in both metrics in the same season since our charting began in 2005. (The others: Darrelle Revis in 2009 and, surprisingly, Corey Graham in 2014, though Graham was barely over the minimum to be ranked.) Peterson had a rough 2014 by his standards, with a drop in performance coinciding with blood sugar issues as he dealt with Type 2 diabetes, so it was great to see him return to form as one of the very best cornerbacks in the league.

Rounding out the top five were Cincinnati's Adam Jones, San Diego's Patrick Robinson, Carolina's Josh Norman, and Indianapolis' Vontae Davis. While Jones certainly played a major role in the Bengals' playoff meltdown against Pittsburgh, his performance during the regular season was a big reason why the Bengals were hosting that game as the third seed in the AFC.

Patrick Robinson excelled in 2015, allowing only 4.9 adjusted yards per pass in his first year with the Chargers. Robinson spent the first five years of his career in New Orleans, which is not exactly a defensive powerhouse these days, so trading in the shores of the Gulf of Mexico for the shores of the Pacific Ocean was definitely a good career move for the 28-year-old out of Florida State. Robinson put up good numbers as a No. 2 cornerback in 2014 (21st in adjusted yards per pass, 27th in adjusted success rate) and he continued to excel in 2015, playing mostly in the slot between Brandon Flowers and Jason Verrett. Vontae Davis and Josh Norman had posted high marks in 2014 as well, ranking as the No. 2 and No. 4 cornerbacks from the 2014 season by adjusted success rate, respectively. Last season brought more of the same by that metric, as we see below.

Norman and Davis finished third and ninth by adjusted success rate in 2015, but the difference between the two of them was only three percent. Joining Norman in the top five were Atlanta's Robert Alford in second, Pittsburgh's William Gay in fourth and then Peterson (first) and Jones (fifth) again.

Davis ranks as one of the best acquisitions Colts general manager Ryan Grigson has made in his time in Indianapolis. Before the 2012 season, Grigson traded a 2013 second-round pick to Miami for the 2009 first-rounder and re-signed Davis to a four-year contract in 2014. Outside of the trade for Davis and the drafting of Andrew Luck and T.Y. Hilton, Grigson's track record has not been great. If anyone knows where to get a first-round pick in a trade for a running back, please let me know.

Peterson's 70 percent adjusted success rate was well ahead of the rest of the field, as Alford in second was closer Dallas's Byron Jones in 12th than he was to Peterson in first. Alford put up an adjusted success rate of 65 percent in 2015, but teams still preferred to target the 2013 second-round pick instead of going after his counterpart, Desmond Trufant. The two young corners were among the few bright spots for an Atlanta defense that finished 22nd in defensive DVOA in head coach Dan Quinn's first season with the Falcons. Hopefully the outlook in Atlanta will improve with more time to adjust to Quinn's defensive system.

Seeing Norman at the top of these charts is no surprise, but it is worth noting that a play may be deemed a "successful" play for a cornerback even if he gets beat. If a pass falls incomplete, it goes down as a successful play for the cornerback in coverage. That includes inaccurate passes and even drops, so when Odell Beckham drops a wide-open touchdown, Norman still gets credit for a successful play. Adjusted success rate may be imperfect, but it is definitely still a useful measure of defensive play. While Norman got lucky against the Giants, he wouldn't have finished in the top five just on lucky breaks alone. In other words, he's still a darn good player, which he put on display against New Orleans in Week 3.

(Ed. Note: We've considered counting drops against cornerbacks in the future; we may do some testing to see if this helps make cornerback charting metrics more consistent from year to year. Overall, these plays tend to balance out plays where a cornerback has good coverage but the receiver catches the ball with excellent effort anyway. -- Aaron Schatz)

Missing from 2015's top ten in adjusted success rate after making it in 2014 were Sam Shields (20th in 2015), Richard Sherman (21st), Chris Harris (39th), Xavier Rhodes (60th), Brandon Flowers (72nd!) and E.J. Gaines (who missed 2015 with a Lisfranc injury). What was that about cornerback statistics being incredibly volatile from year to year?

Finally, we will take a look at the best cornerbacks by estimated target rate.

Leading the pack this time was William Gay at 11.2 percent, followed by Jacksonville's Aaron Colvin, Green Bay's Casey Hayward, Peterson (again), and San Francisco's Jimmie Ward. Ward comes with an asterisk as he split time between corner and strong safety, so you could argue that Trufant should be in fifth place instead.

For the past few seasons, Trufant has been considered one of the best young cornerbacks in the NFL. While true, this may be the year when the word "young" gets dropped from that description and we simply consider Trufant one of the best cornerbacks in the league, full stop. As mentioned above, Atlanta's defense was not a good one in 2015, but if they do end up shooting up the rankings this fall, Trufant and Alford will likely be a large part of the reason for the improvement.

Gay checks in again as one of the best cornerbacks in the league by success rate and the clear top cornerback for the Steelers. The 31-year-old remains one of the last holdovers from the dominant Pittsburgh defenses from the late 2000s, and his performance over the past several years has been quietly spectacular. Gay does not post the gaudy counting stats like interceptions (11 in his entire nine-year-career) that would send him to the Pro Bowl, but Mike Tomlin and company have to be extremely pleased with his play. Unfortunately for Pittsburgh, that does not extend to the other side of the field. Fellow starter Antwon Blake will be getting some substantial coverage in Wednesday's article, so I'll leave it at that for now.

It seems a little strange that Colvin was targeted so infrequently, given that he ranked 41st in yards per pass allowed and 36th in adjusted success rate. Jacksonville's other starter, Davon House, finished 40th and 50th in those two categories and was targeted very frequently, but a lot of the difference was likely due to the receivers he was tasked with guarding, such as Houston stud DeAndre Hopkins.

Hayward's numbers were quite good across the board, finishing 13th in yards per pass allowed and 19th in adjusted success rate. However, his lack of targets faced had a lot to do with his position in the slot as well as the other cornerbacks in the Green Bay secondary. Sam Shields put up solid, if not spectacular numbers, but Damarious Randall finished near the bottom in both yards per pass and adjusted success rate, and he was targeted the sixth-most frequently in the league.

One player I would like to point out as an interesting case was rookie cornerback Marcus Peters in Kansas City. Peters was one of the most frequently targeted cornerbacks in the league (25.8 percent, good for seventh-highest target rate), but he ranked 15th in adjusted success rate. All those targets allowed the rookie to tie for the most interceptions in 2015 with Cincinnati safety Reggie Nelson at eight apiece.

Next up on Wednesday, we will continue the discussion of cornerback charting statistics. However, instead of focusing on the best performers from 2015, we will be taking a look at the players who struggled defending the pass.