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Worst CB Charting Stats (and More on the Best)

Worst CB Charting Stats (and More on the Best)
Photo: USA Today Sports Images

by Andrew Healy

In 2013, Trumaine McBride posted the best charting stats of any cornerback in terms of both adjusted success rate and adjusted yards per pass allowed. Now, the rental car agreement-length disclaimer in that article made clear that although McBride had posted the best numbers for that year, he was in no sense the best corner in football. Still, McBride's ascension to the top of the heap certainly felt odd, and his performance was not repeated in 2014 in his limited snaps. (McBride was slightly above average, on only 15 charted targets.)

To get more meaningful rankings this year, we made a change in last week's "best cornerback stats" article: we split cornerbacks into two groups, No. 1 corners and others, imperfect though those distinctions may be. However, after reading some of your feedback, we wanted to do a little bit more to try to reduce the volatility in cornerback charting stats. So instead of just ranking by one measure, this week we rank players by an average of our two main measures, adjusted success rate and adjusted yards per pass. Doing this kind of averaging usually leads to more reliable and stable measures in social science research.

Even now, these stats constitute just a piece of a larger player evaluation puzzle. The top-ranked player is still not necessarily the best. But the averaging should make this a little less like the World Series of Poker, where the winner sometimes might not even be that good at poker (e.g., Jamie Gold, for those of you keeping score at home), and more like a situation in which the top prizewinner is likely to be very good even if not the absolute best. Kind of like the NFL playoffs.

As with last week, corners are divided up as best we can into No. 1 corners and others. In all cases but two (Vontae Davis and Chris Harris), we simply defined the top corner for a team as the one who faced the most targets against opponents' top receivers (itself not always perfectly clear). This leads to clear definitions in many, but not all cases. Reasonable alternatives for the No. 1 corner could be offered for some teams such as the Eagles.

Last week's article has the sundry details and disclaimers, so let's jump right into the stats. I will be briefer with the discussion of the best corners since much of that appeared in last week's piece. Since adjusted success rate and adjusted yards per pass are on different scales, I turned each into a z-score before averaging them. All cornerbacks are then ranked by that average of the two z-scores, which I call "Corner Index."

"Leading Role" corners are ranked below out of the 32 No. 1 cornerbacks. "Supporting Role" corners are ranked out of the 45 other cornerbacks who had at least 50 charted targets and eight games started.

Best Cornerbacks in Leading and Supporting Roles

Best Leading Role Cornerbacks by Average of Adjusted Yards Per Pass and Adjusted Success Rate, 2014
Player Team Games
Started
Charted
Targets
Pct Team
Snaps
Est
Tgt%
Adj
Yds/Pass
Rk Adj Success
Rate
Rk Corner
Index
Rk
Chris Harris DEN 16 75 91.3% 17.2% 5.1 1 59% 3 1.51 1
Josh Norman CAR 10 62 61.5% 24.8% 5.1 2 59% 4 1.51 2
Vontae Davis IND 15 70 78.6% 22.9% 6.8 8 61% 2 1.11 3
Darrelle Revis NE 16 69 92.8% 17.0% 7.3 12 62% 1 1.03 4
Richard Sherman SEA 16 62 98.7% 17.5% 6.5 7 59% 5 1.03 5
E.J. Gaines STL 15 75 89.0% 24.8% 6.2 5 57% 9 0.94 6
Xavier Rhodes MIN 16 78 94.9% 22.1% 6.3 6 57% 8 0.91 7
Sean Smith KC 16 81 97.6% 19.9% 6.0 3 55% 12 0.83 8
Johnathan Joseph HOU 16 103 76.1% 28.7% 6.0 4 52% 16 0.55 9
Sam Shields GB 14 68 75.0% 23.5% 7.8 18 58% 7 0.49 10
Patrick Peterson ARI 16 93 91.5% 24.3% 7.1 11 55% 11 0.45 11
Stephon Gilmore BUF 14 63 77.1% 20.2% 7.4 13 54% 13 0.26 12

Comments

56 comments, Last at 20 Jun 2015, 6:44pm

3 Re: Worst CB Charting Stats (and More on the Best)

Probably just counts INTs as a success for the defense considering that Fuller would probably not rank in the basement if he got much credit for his 4 picks. Interesting to see these stats compare with the star treatment the announcers gave Fuller during games; goes to show how dangerous it is to rank a corner based on a handful of telegenic plays.

17 Re: Worst CB Charting Stats (and More on the Best)

He was a young player who showed promise on an otherwise awful defense, he got praise well into the year.

In some ways he did deserve credit for occasionally looking promising when very few other players did. I wouldn't be surprised to see him get much better with good coaching in the next year or two.

43 Re: Worst CB Charting Stats (and More on the Best)

Not only did he not get a lot of help, he seemed to get thrown into an absurd amount of man coverage with guys like Calvin Johnson, Dez Bryant, and Mike Evans. When Tillman went down, the Bears didn't have a corner to match size with those guys, and they seemed hellbent on keeping Jennings on the left side of the defense.

9 Re: Worst CB Charting Stats (and More on the Best)

Grimes only had two PD and 0 INTs the last 7 games of the year. Which might suggest his second half and first half had a large split. Given the depletion of the whole Miami secondary during the second half of last season I don't know if it was due to a change in the schemes Miami used him in or if he really did run out of gas...

10 Re: Worst CB Charting Stats (and More on the Best)

Aaron has pointed this out but the year to year swings in pass coverage are simply astounding. Fast forward to next year and I wouldn't be surprised to see none of the corners listed above to be on the list. In fact, take out a handful of the top 5 or 6 corners and you're likely see massive swings year to year.

Why? Is it that the individual corner play is so erratic week to week while say offensive line/wide receiver/ tight end play is more stable?

More than likely, despite access to charting, we just don't have a good way of isolating individual play of the defense. Everything is so intertwined.

11 Re: Worst CB Charting Stats (and More on the Best)

Isn't a big part of it that we don't know what the scheme is? For example, this article claims Bradley Fletcher was "left on an island" - watching the games, I don't think that's true. The Eagles did play man-press, but Fletcher always had inside and over the help top, he wasn't out there in single coverage almost at all that I saw. And some of the worst burns he suffered (the second Cowboys game for example) came when Nate Allen clearly was wildly out of position. And that's without even factoring in how pass rush and the CB playing opposite effect the whole shebang.

I think treating good CB play as an individual accomplishment probably doesn't make sense except in the extreme cases like Revis and Petersen where they literally are on their own with no help even glancing their way and still able to put up good numbers. Vontae Davis and William Gay, whatever they're doing out there, they're doing in conjunction with the team, very specially with their safeties.

I mean it won't shock me if Fletcher is ok in New England, even though I hated his guts in Philly. I mean, will anyone be surprised if Cary Williams does well in Seattle? Of course not.

13 Re: Worst CB Charting Stats (and More on the Best)

Only 3 CBs ranked in top 15 in Adjusted Success Rate in 2013 AND 2014
Vonte Davis (#7, #4)
Chris Harris (#6, #6)
O.Scandrick (#11, #13)

I think a big part of the high variance is QB accuracy. Some corners probably just have fortunate seasons in that so many of the passes thrown to their assignment aren't catchable. We can debate for hours how much of an impact their coverage has on the accuracy, but I doubt it's the main reason.

20 Re: Worst CB Charting Stats (and More on the Best)

This analysis also has the weakness of only looking at plays where the corner was thrown at which a)limits the sample size and b)introduces some selection bias since a player is more likely to be thrown at when in bad coverage than good--I imagine this is especially true of top corners like Sherman and Revis, whom opposing QBs are looking to avoid unless given a good reason to attack them. Cian Fahey has done some analysis in the past where he looks at the all-22 for every single snap in coverage for a given player, but unfortunately it's too time consuming to perform for anything but a handful of top corners. And that analysis is even more subjective than these charting methods; at least the charting project here objectively breaks each play down into "offensive success" or "offensive non-success" based on yards gained, whereas analysis like Cian's or PFF's depends on a more subjectively rating each play in coverage.

Both methods have strengths and weaknesses, and the best way to judge a player probably involves a little bit of both. Anyways, these numbers are much better at showing us that, say, Vontae Davis is much better than Bradley Fletcher, than they are at distinguishing between Davis and Sherman at the top.

27 Re: Worst CB Charting Stats (and More on the Best)

I agree with both points you made at the end. I think there is a tendency to grade people based on reputation when watching them in coverage. On Grimes, for example, I suspect that reputation is why he graded well. I'm not saying I know this for sure because I saw only some of his snaps, but it seems to me like the objective charting numbers better capture his play.

And agreed on the numbers being better at giving broad patterns than fine distinctions between players.

29 Re: Worst CB Charting Stats (and More on the Best)

I could't disagree more - the exact problem is that you can't tell the difference between Fletcher and Davis even with these numbers. Next year, they could easily be flipped - it's the more marginal talents like Davis and Fletcher that have the most erratic swings. I think the consistency of Revis shows he's definitely better than Fletcher, so that's a case of the stats confirming what you would think is true. (Which is useful.)

I don't think anyone expects even advanced stats to settle the fine distinctions between two world-class players like Revis and Sherman - it's the frustration of these numbers that I wouldn't trust them to mean that if you flipped Fletcher and Davis in 2014 that the Eagles #2CB would've been better and the Colts' #1CB worse. Again, does anyone doubt that Fletcher could easily end up on the Top CB's list after entering into a better situation with a much smarter coach and somewhat better safety support in New England?

The entire problem is that you can't trust these numbers to say anything meaningful about the skill level of more middle-of-the-pack guys like Davis and Fletcher.

34 Re: Worst CB Charting Stats (and More on the Best)

Anything could happen in one year, so it's not impossible that Fletcher could rank higher than Davis - and as I said in another response, I certainly think the situation matters a lot so that Fletcher is likely to rise with McCourty instead of Allen and with smarter coaching. But I sure think it's unlikely that he'll pass Davis. And I don't agree that Davis is a middle-of-the-pack guy. He's now been top ten in adj success rate two years in a row (in 2013 he was 7th among all corners). If he got a bonus for tackling, he could be even higher. In general, randomness is a less likely explanation for guys like Davis who rank high repeatedly.

41 Re: Worst CB Charting Stats (and More on the Best)

I think you hit the nail on the head. 60-100 plays a season perhaps just isn't enough to draw meaningful conclusions, in most cases. It's only going to take a couple bad games, or games in which a player is hurt, or games in which a player is asked to perform an assignment of which he is incapable, to torpedo his season. And of course, a corner having a bad day, or out of his depth, is more likely to be thrown at. The 'bad days' constitute more of the sample than the 'good days', one would assume.

So I think this is an area where I would trust the scouting numbers more, purely for the sample size they bring. But then, as you say, that is subjective and does not adjust for opponent. I do appreciate the work being put in, but I can't have a lot of faith in the conclusions either way.

44 Re: Worst CB Charting Stats (and More on the Best)

Football analytics are still very young. I appreciate that FO, and their cohorts, are trying to quantify some things that previously hadn't been. (If we can believe FO commenters, there are 2 good offensive lines in the league and 30 atrocious ones.) This is all still a work in progress, and it's fair to question the work as it goes along.

45 Re: Worst CB Charting Stats (and More on the Best)

We have to define "good". I feel like its even more extreme when it comes to secondaries. If you read SCFB - theres no one secondary outside of the great northwest that they like.

In fact, thinking it through - which teams really have a good secondary? The pats would have, but they lost both corners so we're relegated to what? The jets, the bills, broncos, seahawks, possibly the packers and...what else.

30 Re: Worst CB Charting Stats (and More on the Best)

Sometimes thinking about how intertwined things are just puts the stats into better context (i.e. the Jets' coverage being even worse for coming with such a good front four). But in general, the intertwinedness operates on so many levels. Pass rush, safety help, scheme decisions, the other corners (e.g. Richard Sherman could help Byron Maxwell's success rate by causing QBs to target Maxwell even when he has pretty good coverage).

33 Re: Worst CB Charting Stats (and More on the Best)

It'd be interesting to see the CB stats broken down in terms of a comparison between the #1CB and #2CB on a team (or even throw in the nickel back.) I'm not sure what it would reveal, but it definitely be a cool thing to throw into the mix as far as understanding these stats in context.

Do the best #1CB's frequently have good #2CB's or is Sherman/Maxwell scenario you describe (where a ball is being forced into Maxwell's tight coverage and helping his success rate) indicative of only the very best CB's? Does a big drop-off between Vontae Davis and his #2CB demonstrate how safety help is pumping up Davis' numbers and show how the #2CB has less help? It would be cool to consider.

When I look at the Eagles, I see the disparity between Boykin (very good), Williams (good) and Fletcher (bad) and I'm not sure what it says - comparing it to other teams' breakdowns might be instructive. To me, Williams and Fletcher were equally underwhelming, but is that illusory and the numbers are a corrective? Or do they show something else? It'd also be interesting to see it next to the team's overall pass DVOA and sack rate...) The Eagles had a good sack rate and a bad overall pass defense - seems to me what appeared to be true: if the sack didn't get home, the coverage wasn't there...

42 Josh Norman

As a Falcons fan, I can definitely confirm that he was one of the few CBs last year to have a firm grip on Julio Jones. Which, I guess, is not among the easy things to do as a CB. In total Julio caught 7 of 14 for 69 yards and 0 TDs in 2 games against Norman. His speed definitely makes him an tricky CB to play against, and he certainly is underrated in that regard.

22 Re: Worst CB Charting Stats (and More on the Best)

This is in reply to some points made previously in the first CB Charting article.

First, Byron Maxwell's cap number is just $600k more than Cary Williams' for the 2015 season. Maxwell's number is $8.7M, Williams' was $8.1M. Also, Maxwell's deal is essentially a 2 year deal, they can cut him after 2016 and save money against the cap. It's not like that are paying Maxwell 2 or 3 times what they would have paid Williams. Let's not forget Williams is the guy who skipped OTA's in 2013 to go sconce shopping and complained last year that practices were too hard.

Second, the Eagles canned their DB coach from last year and replaced him with Cory Undlin from Denver. http://www.phillymag.com/birds247/2015/06/03/undlin-making-a-great-first-impression/

23 Re: Worst CB Charting Stats (and More on the Best)

"First, Byron Maxwell's cap number is just $600k more than Cary Williams' for the 2015 season. Maxwell's number is $8.7M, Williams' was $8.1M."

No it isn't. Maxwell's number is right, but Williams' cap hit is only $4.7M.

http://overthecap.com/player/cary-williams/2008
http://overthecap.com/player/byron-maxwell/1535

And since you mentioned it, Williams' deal is essentially a 1-year deal. Cutting him in 2016 incurs only $2.3M dead money, compared to $3.6M if Maxwell is cut after two years. And if both were to happen, Maxwell would've had an average cap hit of $9.2M, which pretty much is twice as much as Williams.

26 Re: Worst CB Charting Stats (and More on the Best)

Looks like it was the last year of his contract, seems like it would have been easy to extend him lowering his overall cap number. Also, by this measure you have to add the dead money cap space to Maxwell's number since that's the cap space it costs to swap Williams for Maxwell which means + 1.6 million.

31 Re: Worst CB Charting Stats (and More on the Best)

But they did have the option of not signing Maxwell to an awful contract. It's fair for the author to say "If you pay Maxwell almost three times what you paid Williams in 2014, they should be expecting a decisive and significant upgrade on Williams' 2014 level of performance." That Williams would've been expensive to keep around this year is largely irrelevant to the point being made.

37 Re: Worst CB Charting Stats (and More on the Best)

Williams' cap number was $6.4M in 2014, they are not paying Maxwell $19.2M in 2015 or anything remotely close to it. It is not fair to say something that is patently false.

There options were:

1) keep Williams at $8.1M
2) cut Williams,eat $1.6M in dead money,sign Maxwell at $8.7M
3) cut Williams,eat $1.6M in dead money,sign someone else for less

They clearly were not interested in Option #1, they never approached Williams about an extension or renegotiation that would reduce his 2015 cap number. Given his performance and his complaining, Williams was a goner.

So, there choices were #2 or #3. Aside from Revis, Maxwell was pretty unanimously the #1 free agent corner. So, they could pay $2.2M more than they were going to pay Williams and get the best remaining free agent CB to replace him, or they could sign someone else.

Given that Williams' cap hit with Seattle is $4.7M, and assuming they wanted an upgrade on Williams(which I think is a reasonable assumption), they needed to find a better player than Williams who would have a cap hit of between $5M and $8M(what Williams got from Seattle and what he would have gotten from the Birds). So, if you are going to excoriate Kelly for his choice, I think you should point out the players they passed up in the price range who fit their scheme, etc. The free agents who actually signed contracts on that range were: Antonio Cromartie, Chris Culliver, Tramon Williams, Buster Skrine, Davon House, Perrish Cox and Brandon Browner.

Cromartie and Culliver don't seem like culture fits. Skrine is too small. Perrish Cox is on the worst corner list. Tramon Williams is older than dirt. Davon House has less of a track record than Maxwell. That leaves Brandon Browner I think. Am I missing something ? Is choosing to spend the coin for Maxwell instead of Browner THAT bad a decision ? I have to give Chipper the benefit of the doubt on this one.

38 Re: Worst CB Charting Stats (and More on the Best)

Or they could have kept Williams, saved cap space and (according to these numbers) fielded just as good of a player. Only one that's been a starter for a full season in the NFL, has been a #1CB, has a lower penalty rate and hasn't been supported by likely the greatest secondary ever assembled in the NFL (a secondary which, it should be noted, was just as good for several years running without Maxwell and his 12 starts.)

The secondary had too many problems for the Eagles to fix them all simultaneously (in doing so, they risked, say, heading into the OTA's without a starting safety on their roster) and trying to fix the Cary Williams problem by signing by what is all appearances another player almost identical to Williams is definitely something that deserves no benefit of the doubt. We all just saw it fail. Failing to sit tight with Williams in order to pay more money for Maxwell demonstrates the combination of shortsightedness and intransigence that is so far Kelly's hallmark as a GM.

You're absolutely correct: it was a very weak market for CB's. Smart teams (New England, Seattle) that had holes waited for the dust to clear and signed cheap veterans to reasonable rates rather than overpaying for Byron freakin' Maxwell.

I mean, look at the secondary they've assembled:
CB1: Byron Maxwell
CB2: unknown
S1: Malcolm Jenkins
S2: unknown

If if they wanted to sign Maxwell, keeping Williams around would've been a good idea. If Maxwell (who, again, has never played a full 16) gets injured, what's the plan? I mean look at that! Look at the mess they made back there! They took the weakness of the team and made it weaker. It's almost inconceivable how much they have riding on a 2nd round pick and two Seahawks cast-offs. Nate Allen and Jaiquawn Jarrett were 2nd round picks. Why should there be an assumption Rowe will even be THAT good?

47 Re: Worst CB Charting Stats (and More on the Best)

Well, considering these CB charting numbers say Williams was BETTER "in a supporting role" and I listed several reasons above why IN CONTEXT (apart from charting #'s) there's a half dozen reason to think Maxwell will be worse as a #1CB than Williams, I think you have said literally nothing of value in this reply.

You realize the charting numbers are literally the only thing Maxwell has going for him in comparison to Williams, right? I'll repeat what I said above.

Maxwell:
Has never been a #1CB.
In four years in the league, has never been a starter for a full season. Before this year, he barely played.
Was supported by probably the greatest secondary ever.
Accrued more penalties in fewer games (and far fewer snaps.)
Was literally replaced by Williams in Seattle.
Is being paid more than Williams by a healthy amount.
The Seahawks have consistently gotten great production from their #2CB spot, regardless of the player. (Thurmond, Browner, Lane, Maxwell.)

The most generous reading of Maxwell is that he is of equal abilities to Williams and the only evidence for that generous reading are the numbers you are quick to point out don't mean that much (I agree!) The only support for the generous reading of Maxwell's talent (a reading I don't believe in, by the way - I think there's a strong chance he's going to be much, much worse the reasons listed above) is the numbers.

So, yes, you do have a point: there's no reason to think Maxwell will be nearly as good as Williams was in 2014. If you put the numbers in context, he's much, much worse of a prospect.

49 Re: Worst CB Charting Stats (and More on the Best)

I'm sorry, "the most generous reading of Maxwell based on any verifiable facts." Feel free to give me a fact or two that allows for a more generous reading!

"He looked ok his 3/4 of a season as a starter!" and "he was a really coveted free agent!" have been covered.

I'm really all ears - seriously, I'd love to switch out of the mindset I'm currently in, which is "the best thing for the Eagles will be for them to go 1-15 and get Kelly fired before he can screw up the 2015 off-season and really ruin their future by getting rid of Cox, Boykin and Kendricks while signing Sam Bradford to a longterm deal or giving up 3 first round picks to get the QB that 'no, seriously you guys, this guy is the one who will make the difference' then after a few 8-8 type seasons going back to college."

I think Eagles fans rooted for a well run team with a competent coach for so long, they've forgotten what can happen when the person in charge makes terrible decisions and how a franchise can get run into the ground very easily. Two year from now (and for the record, I think they could probably go 9-7 or 10-6 this year if a few not-crazy things go right for them) when they're a debacle, don't say "how did this happen, it came out of nowhere! he went 10-6 his first three years!" I'm telling you right now it's already happening - the sky doesn't fall suddenly and without warning, it's a black cloud that slowly descends on a franchise and engulfs it gradually.

There are heaps of bad, bad decisions being made by Kelly as a GM - Maxwell's probably not the worst. Expecting Maxwell to be a better #1CB than Williams while failing to find a clear replacement for Nate Allen or Bradley Fletcher probably comes together as a unit to form his worst decision.

50 Re: Worst CB Charting Stats (and More on the Best)

The biggest fact is that ANY NFL team could have had Maxwell, and ANY NFL team could have had Williams, and Maxwell is being paid $4M more. If it is a FACT that Williams is as good as Maxwell it seems to have escaped the entire NFL. If my choices are to believe the general NFL consensus that Maxwell is better, or believe you, I'm going with the NFL crowd. Sorry.

Also, Williams benefited from being the corner opposite Fletcher, why on Earth would anyone have thrown against Williams, when you could be toasting Fletcher all day long. Now, Williams goes to a situation where he is going to be the guy who gets picked on. If he posts numbers as good as Maxwell I will be shocked. I don't know who else Seattle has at CB but I wouldn't be surprised to see Williams demoted during the season. Prior to Fletcher's 2014 meltdown, I thought he was a better CB than Williams, I think Williams will be brutally exposed this year.

25 Re: Worst CB Charting Stats (and More on the Best)

Verner is one place where FO and PFF disagree really strongly; they charted him as very good last year, and FO's stats hate him. I'm assuming that, if you split the year, even FO would like him better, as he started off pretty brutal and seemed to settle in and play quite well at the end of the year.

Interestingly, things are flipped for Lavonte David; he's way up in Defeats at FO (per usual), but PFF was pretty down on the year he had.