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31 Jul 2012

Film Room: Understanding Cornerbacks

by Andy Benoit

The trade that sent Asante Samuel from Philadelphia to Atlanta this past offseason was a little odd. It’s not often we see a player sign a three-year, $14.5 million contract upon being dealt for a measly seventh-round pick. That’s a lot of money for a player whose worth was deemed by his former team to be almost nothing. In some ways, it's a fitting transaction for Samuel. Not because the 31-year-old might be in steep decline, but because he’s always had a unique sort of value.

Samuel excels in FO's game charting metrics, and he has long been regarded as one of the best off-coverage corners in the NFL, but an "off-coverage" corner is all he is. Telling a corner he’s great in off-coverage is somewhat of a backhanded compliment –- like telling someone they are a lot of fun when they're drunk. (Thanks! ...Wait ... only when I’m drunk?) Samuel’s strengths include identifying route designs and making breaks on the ball. His weaknesses are jamming receivers at the line, bump-and-run plays that are headed downfield, responding to sudden changes of direction, and anything remotely related to tackling. There is practically zero physicality to his game.

Samuel in a nutshell: a great playmaker, but a limited one. A corner that specializes in off-coverage is generally someone who is good in zone and iffy in man-to-man. When they do play man, it’s almost always off-man, which is essentially man coverage with a cushion. In that design, the corner’s aim is to keep the receiver in front of him and the quarterback in his line of vision.

Most zone corners plays off-man regularly each game, as virtually every type of coverage, with the exception of a classic Cover-2, involves some sort of man principles. A great example is Cover-3, a coverage in which the outside corners each take a third of the field while the deep safety handles the middle. In a Cover-3, it makes no sense for a cornerback to just line up and guard the grass in his area, as quarterbacks not named Donovan McNabb don’t randomly throw at grass. The corner’s job, rather, is to locate and defend any receivers who come into his area.

Because they’re usually able to see the quarterback, off-coverage corners are often the ones making interceptions. The great ones disguise their intentions and bait quarterbacks into throws. Few players have done this as well as Samuel, and consequently, quarterbacks have developed a healthy fear of throwing to his side of the field. Analysts usually feel smart pointing out that "Joe Quarterback hasn’t even thrown to Samuel’s side this game." Too often, though, their follow-up comment involves mistakenly designating him as a "shutdown corner."

Samuel is not, and has never been, a shutdown corner. On one out of every five occasions, Samuel might jump a pass and either knock it down or take it back for six. But with his perpetually soft cushion, a great quarterback knows that he could, theoretically, go after Samuel. He could do that by throwing at him, but the offense also could run at him and manipulate other play designs to capitalize on his distinct weaknesses. What’s more, those distinct weaknesses hinder how Samuel’s coaches use the defensive backs around him. It can be very tough to sprinkle variety into your defense when one of your corners constantly plays with a soft cushion. This is why Samuel's value doesn't match the numbers he puts up in FO's game charting metrics. Yes, Samuel has led all starting cornerbacks in Adjusted Yards per Pass for two straight seasons, but his style of play opens up ways for the offense to get yardage in other ways.

You could argue that Samuel’s opposite is Nnamdi Asomugha. The ex-Raider is an elite press-man corner who struggles in off-coverage. Asomugha’s long, sturdy frame and fluid change-of-direction in a backpedal have made him a great man-to-man defender. But Asomugha doesn’t move well when coming from a standstill; he doesn’t react with a quick twitch to things he sees. (The Eagles, amazingly, didn’t seem to recognize this last season when they played him in the slot and at dime linebacker, but that’s another discussion.)

While Samuel has to be reactive in his coverage, Asomugha has to be proactive in his. Asomugha can shadow a receiver, but the catch is that he’s got to be able to exert some physical influence over where that receiver goes. It’s not just about getting jams and pressing –- it can’t be, given how the NFL frowns on physical coverage downfield. Asomugha has to influence receivers with his positioning. His goal is usually to force a receiver towards the sideline. That gives a receiver less area to run his route, which makes him easier to shadow. Cornerbacks who rely on using the sideline to their advantage are often referred to as "boundary corners." Asomugha is the best boundary corner in the NFL.

Perhaps it was erroneous earlier to refer to Asomugha as "an elite man-to-man defender." Really, he’s elite in man-to-man on the boundary side of the field. Playing pure man-to-man in space, Asomugha is merely very good. That still makes him one of the game’s best, but there’s a notable difference between his ability on different sections of the field.

Very few cornerbacks are truly elite in pure man-to-man. That’s why it is so hard to find quality nickel backs. A cornerback covering the slot almost has to play man-to-man because it’s too difficult to clearly identify and defend zones in the short middle of the field.

Due to the difficultly of consistently shadowing NFL receivers, a lot of slot corners play a trail technique in man, which basically means they stay on a receiver’s hip pocket. This kind of coverage requires safety help over the top. It’s very liberating for the corner, as he has room to recover from his mistakes and, unlike a boundary or zone corner, he doesn’t have to operate out of a backpedal.

What’s rare is finding a cornerback who has the recovery speed and innate positioning prowess to play trail and still make plays on balls thrown over the top. The guys who can do this are the elite man-corners -– the ones coaches are willing to occasionally put on an island with no safety help ( Champ Bailey, Joe Haden, Johnathan Joseph, Ike Taylor, to name a few). Often, but not always, the same athletic traits that give a player great recovery speed are the same athletic traits that allow him to effectively break on a ball. Thus, the elite man-corners can usually thrive in zone.

Elite man-corners are not shutdown corners, though. Shutdown corners are the guys who can play all types of coverage against all types of receivers. They’re the guys defensive coordinators build entire schemes around. Often, really good man-corners, particularly the physical ones like Ike Taylor and Johnathan Joseph, can look like shutdown corners because their coaches will build schemes that put them in isolation coverage. However, the coach does this figuring the corner will surrender five or six completions -– a worthy tradeoff for the freedom of having 10 guys to use elsewhere. A coach with a shutdown corner, on the other hand, assumes his superstar will give up no more than one or two inconsequential completions a game.

Generally, shutdown corners play man-to-man because a) It’s a straightforward approach that suits their ability and b) They don’t have any safety help, so they have to play man. Sometimes that man coverage is a Samuel-styled off-man, sometimes it’s an Asomugha-styled press near the boundary. Most often, though, it’s in the form of trail technique, as that’s easiest and best way to prevent passes from even being attempted. The true shutdown corners have the recovery prowess to play trail technique with no safety help.

Currently, there is only one shutdown corner in the NFL. His name is Darrelle Revis. But, there may be a second in the making in Arizona: Patrick Peterson. The No. 5 overall pick of the 2011 draft drew plenty of shutdown assignments late last season. Remarkably, he played trail technique almost exclusively, even on the outside, where off-man or press-boundary usually prevail. Peterson has unwavering faith in his recovery ability.

The takeaway here is that not all highly-regarded cornerbacks are equal. It’s very difficult, perhaps even impossible, to find statistics that accurately portray a corner’s true value. There are just too many variables in the actual playing style that can't be properly expressed through numbers, so any advanced metrics need to be seen in context. Samuel has been to four Pro Bowls; Taylor has been to none. Samuel is the more dangerous player, but Taylor has allowed his team to do more schematically. It's my guess that most coaches would rather have Taylor than Samuel.

When evaluating cornerbacks, instead of focusing simply on how the guy is playing, focus on how he is being used. That will tell you a lot about him.

Follow Andy Benoit on Twitter: @Andy_Benoit.

Posted by: Andy Benoit on 31 Jul 2012

37 comments, Last at 06 Aug 2012, 11:04pm by JM

Comments

1
by tuluse :: Tue, 07/31/2012 - 11:43am

Would you consider Champ Bailey in his prime a shutdown corner?

"When evaluating cornerbacks, instead of focusing simply on how the guy is playing, focus on how he is being used. That will tell you a lot about him."

Is there any good way to do this with normal TV angles?

4
by Theo :: Tue, 07/31/2012 - 12:09pm

Where he lines up, if he runs with the guy, or stays in his zone, is he being aggressive vs the receiver or is he giving him a cushion.
Is that what you mean?

6
by tuluse :: Tue, 07/31/2012 - 12:27pm

I can tell if a guy is lining up off or not (it frustrated me to no end when the Bears wouldn't let their corners jam for games on end), but seeing that how do you tell if it's man, cover 3, some sort of weird hybrid, etc?

8
by Karl Cuba :: Tue, 07/31/2012 - 1:01pm

If the defenders are following people across the field then it's man coverage. It can get confusing when the defense starts to play man coverage with cut/slice technique where defenders hand off crossing receivers in order to maintain leverage.

11
by Theo :: Tue, 07/31/2012 - 2:05pm

If they are smart they won't sell it pre snap. But lining up outside, hips towards the QB and not the receiver is a good indication of zone.
Lining up inside, hips pointing at the receiver - good indication of man.
During the play - looking into the backfield and looking around for other receivers is a good indication of zone.
If he runs with a man - then it wouldn't surprise you it's probably man. More than 5 man pass rush? Probably man.
Check the outside linebackers. Blitz? Man. Drop? Zone. Stay with their man? Man. Cleveland Browns? No one knows. Not even the players.

Little keys like that, but often the camera doesn't show that much and the plays go so fast, you can't tell.

21
by Greg F (not verified) :: Tue, 07/31/2012 - 4:54pm

As A Browns fan, I can confirm this.

9
by speedegg :: Tue, 07/31/2012 - 1:57pm

I think a lot of people would consider Champ Bailey a shutdown corner in his prime. He was smooth, strong, and had deceptive speed. If he got beat, he was fast enough to catch up and go hip-to-hip with the WR down the field.

Can't remember if he played press-man or off-man...because I'd get too pissed to remember when he'd turn a sure completion into an INT or pick-6.

And yeah, TV angles don't do the secondary justice. You have to go to the game or wait for the new NFL Rewind.

2
by AnonymousA (not verified) :: Tue, 07/31/2012 - 11:53am

Really interesting piece that unfortunately falls off horribly at the end. After spending the entire thing quantifying types of corners and talking about what they each do well, they "blah blah blah stats can't tell you everything!" made it feel like I was reading Fox Sports.

Is an exclamation of "grit!" now required at the end of any analysis, even on a site like FO?

16
by CraigoMc (not verified) :: Tue, 07/31/2012 - 3:13pm

FO has been pretty upfront about how defensive play in general, and defensive back play in particular, is pretty hard to quantify.

33
by armchair journe... :: Sat, 08/04/2012 - 2:12am

Well yeah, and the general principal of combining statistical analysis with film/observation to get a complete picture, rather than relying on one or the other alone.

I thought this was a fantastic article.

//AJMQB

3
by ebongreen :: Tue, 07/31/2012 - 11:59am

Thanks. This is as clear of a description and a distinction in cornerback technique and how it affects schemes as I've ever seen. More please!

5
by Theo :: Tue, 07/31/2012 - 12:19pm

It's one of the hardest, if not the hardest position in football.

I don't know if stats back this idea up, but I get the idea that more and more corners (and linebackers) are not after taking away the completion, but after stopping the play right there and not allowing any yards after the catch.
They take away anything deeper than a first down, admit that they can't stop the short pass and allow many of them - the trade of being that they allow no yards after.
Of course in the earlt 00's the Cover 2 defense made and won some Super Bowls with this idea in Tampa, Chicago and Indianapolis, but I see almost all teams do it now - not only in zone teams.

7
by Karl Cuba :: Tue, 07/31/2012 - 12:59pm

Good article, a nice analysis of Asante Samuel, a player who I have always felt has been simultaneously over and underrated. However, I have one quibble. Is Ike Taylor really a man corner? Dick LeBeau is pretty famous for playing cover three zones behind both his conventional plays and his zone blitzes.

10
by Xian :: Tue, 07/31/2012 - 1:57pm

Really helpful overview. This will make it much easier for me to explain my frustration with various CBs to fellow fans. Heh.

Packers homer question:

Where does Charles Woodson fall on this spectrum...now and at his peak?

12
by chemical burn :: Tue, 07/31/2012 - 2:27pm

This article is seems like it was written on crazy juice - lots of definitions made up by the author that don't match the colloquial definitions (shutdown doesn't just mean a guy who teams refuse to throw at - like eli Manning explicitly said about Samuel?), appraisals of players that I don't think anyone seriously believes (seriously, more coaches would rather have Taylor than Samuel?) and almost nothing backed up by stats or other hard analysis. If this is where FO is headed, I'm truly disappointed...

13
by chemical burn :: Tue, 07/31/2012 - 2:35pm

Also, if you're going to call your series "Film Room" a single example taken from the film would be nice.

29
by billsfan :: Wed, 08/01/2012 - 5:40pm

I'll second that. Since this "Film Room" article was entirely text, I'd settle for anything visual--links to YouTube highlights, play diagrams, crude MS Paint stick-figures showing cornerback alignments at the snap, the sultry stare of Catholic Match Girl... just give us *something* to look at.

(I also like the Eagles)

14
by Eddo :: Tue, 07/31/2012 - 2:49pm

I disagree. Sure, it's making up some definitions, but it's providing us a way to differentiate different types of corners.

As for Ike Taylor vs. Asante Samuel, I think you'd be surprised. Samuel only fetched a seventh-round pick in a trade, and Ike Taylor is pretty well-regarded across the league.

17
by turbohappy (not verified) :: Tue, 07/31/2012 - 3:25pm

I agree, I think that assertion was probably correct.

18
by tuluse :: Tue, 07/31/2012 - 3:30pm

14.5 million over 3 years is also not very much. He's the 3rd highest paid corner on the Falcon's alone.

19
by Aaron Brooks Go... :: Tue, 07/31/2012 - 4:09pm

He's also a 31 year-old who doesn't tackle. Some of his round-value reflects his future performance as much as it does his present body of work and capability.

15
by RichardD (not verified) :: Tue, 07/31/2012 - 2:50pm

I don't see anything wrong with an FO article pointing out the limitations of statistical analysis in one aspect of the game.

24
by Jimmy :: Wed, 08/01/2012 - 7:39am

There is no single set of football nomenclature that everyone agrees on. Consequently defining terms and then explaining them is pretty much the only option.

25
by t.d. :: Wed, 08/01/2012 - 9:10am

the article is the next gen of Cover 2, which was the successor of Every Play Counts. Football Outsiders has had a regular column like this for at least eight years

20
by NateN61 :: Tue, 07/31/2012 - 4:30pm

The guy has ALWAYS been a zone DB. He cant really play man and that's just how it is. So if a team needs corner that can redirect a WR at the LOS then keep on lookin.

22
by Raiderjoe :: Tue, 07/31/2012 - 11:41pm

Also I twitted a. Benoit but don't understand it. There is a retweet thing and an arrow and another icon. I responded but don know how it came out. A retwit or reply? What is difference? Still haven't gotten used tobywiiter.

23
by StatisticalUnlimited (not verified) :: Wed, 08/01/2012 - 12:00am

This is a fantastic article. I do agree it's worth pointing out that statistical analyses of CBs lack contextual information that often make such statistics useful. However there is one statistic that's incredibly valuable, one that coaches repeat endlessly as mantra: turnovers. Samuel produced picks, and picks (not pick-six) are generally worth about +6 for a team. A defense creating a turnover ends a drive on average about as successfully as that drive was: an offense on the verge loses those easy points, or an offense backed up to its own endzone practically hands points to a defense with a turnover. These extremes diminish as you get closer to the center of the field but a drive is still being ended and given to the opponent. When the Eagles' plus/minus went down the tubes in 2007 they had to do something and that was Samuel. Without Samuel, a declining Lito Sheppard, and a Dawkins reaching a seemingly-untenable age, turnovers were going to have to come from somewhere. And Sameul contributed right away: 4 INTs in 2008 and the 4th ranked team in terms of plus/minus, and a playoff trip that season repeated the next season with the 2nd overall plus/minus. Samuel had 9 INTs and 1 FF in 2009. In 2009 down the stretch the Eagles won four close games. Against the Bears the general fear of Samuel led to no yardage produced his direction. And he saved a breakaway rush from becoming a TD. The next close one the Redskins made the mistake of throwing his way, and Samuel came up with two picks that produced two FGs (because McDirt was floundering already). The next tight win came against the Gnats and Samuel shut down Hakeem Nicks. The last close one the Eagles won down the stretch came against the Broncos, and again, Samuel comes up with a pick where Denver was driving to make the game close. And McNabb nearly vomited a 17 pt 2nd half lead. With these INTs you've basically got a guy who's putting your team in the playoff, and that's one helluva statistic that comes with its own context. In 2010 Samuel comes up big in close games against the Manning brothers, shutting down Eli and picking Peyton twice. Another playoff trip. 2011 is a disaster for the secondary but that doesn't hang on Samuel. There's a scheme problem sure. Every good player has an exploitable flaw. But whatever lack of scheme freedom from not having the single shutdown corner in the NFL doesn't matter much if who you've got is producing takeaways. The value of takeaways is so underrated and so critical. It's what makes it too easy for the Eagles to shed Samuel and to put scheme before success.

26
by Joseph :: Wed, 08/01/2012 - 10:31am

I'll second this general idea. Darren Sharper made a HUGE difference in the Saints secondary in 2009, and his effect on the other guys was quite quantifiable by INT's in general. IMO, GW's tendency to all-out blitz was less effective without Sharper there to read the QB's eyes and pick off the hot read--not to mention his reputation caused QB's to hesitate a split-second, leading to other DB's doing the same thing. Sharper was a liability in run support, sure, but the Saints' D has fallen off the last two years without him.

31
by LionInAZ :: Wed, 08/01/2012 - 10:46pm

I'd say you can put the 2010-2011 Charles Woodson into this category as well.

27
by Eric (not verified) :: Wed, 08/01/2012 - 12:57pm

How would you categorize Raven's cornerbacks Lardarius Webb and Jimmy Smith?

28
by andy (not verified) :: Wed, 08/01/2012 - 2:10pm

It's not so much Patrick Peterson that has unwavering faith in his recovery ability, it's the coaches that do! If Peterson were playing trail all the time because he felt like he could, even though the coaches told him to do something else, then he would get yelled at, right? I find it more plausible that the coaches are telling him to play trail because he can

30
by andy (not verified) :: Wed, 08/01/2012 - 9:56pm

This is a great article - look, anyone who's played football, has done film study, or watched Jaws and Greg Cosell in action (or read their stuff) knows about the concepts the author is talking about.

32
by Dr. Mooch :: Thu, 08/02/2012 - 11:11pm

Stevie Johnson thinks Revis's alleged shutdown abilities need more discussion.

34
by JM (not verified) :: Mon, 08/06/2012 - 10:21am

If you have zone corners who excel at zone coverage and man corners who excel at man coverage, then what exactly is the definition of a "cover corner?" It seems like an odd term in that all CBs "Cover" in some way or another. It's like say this QB is a "passing QB." As opposed to what, a "non-passing QB?"

35
by tuluse :: Mon, 08/06/2012 - 10:42am

Andy never used the term cover corner.

37
by JM (not verified) :: Mon, 08/06/2012 - 11:04pm

i know. it's just one of those CB related terms that bothers me.

36
by Dean :: Mon, 08/06/2012 - 2:21pm

"non-passing QB?"

Vick, Tebow...