Browse > Home /

Who Is the Best Cornerback: Do YPA’s Mimic the SAT?

July 14, 2008

The third story in BSR’s series exploring the question, “who is the best NFL cornerback,” looks at the value of K.C. Joyner’s YPA statistic. Does it measure innate cornerbacking skill, or does it measure performance?

The Educational Testing Service, the creators of the SAT exam, long maintained that their test was uncoachable. It, like all aptitude tests, claimed to measure innate ability, what an individual was capable of achieving, not what a particular student had learned. Therefore, cramming was deemed pointless, since it would not affect a student’s outcome. This belief has been exploded in recent years, as the test has been exposed as having a clear ideological bias.

K.C. Joyner has never claimed that his yards per attempt cornerback stats measure a corner’s aptitude. They are derived from pure empirical study; Joyner looks at tape of each NFL corner each year and measures the number of throws aimed his way, the results of each throw and the number of yards gained against each player. The results would seem transparent.

Nevertheless, readers of this blog reacted to my initial posting of corner YPA averages as if the stat did measure aptitude. Several readers questioned the stats, in part because the top ten CB list did not include Champ Bailey, the Denver corner considered the game’s best by many pundits.

Bailey missed the cut, though not by much (he ranked 14th among CBs with YPAs for every one of the last four seasons). He’s lower because he lacks consistency. Here’s his line, with his overall rank by year in parentheses:

Player-team 2004 2005 2006 2007 Avg.
14. Bailey - Denver
 8.6 (66th) 7.1 (36th) 4.7 (1st) 7.8 (56th) 7.1

As you can see, Bailey’s averages floated in the bottom half in ‘04 and ‘05 before he posted one of the best seasons recorded in ‘06. He dropped back into the bottom half in ‘07, allowing more than three yards more per attempt that year. And it’s not as if Bailey sat on an island most of the game and was then surprised when an opposing QB deigned to throw his way. He was targeted 60 times, only marginally better than counterpart Dre Bly, who saw 78 balls, though Bly’s YPA was an awful 8.8.

Looking at this line, I see a mediocre cornerback, with three fair seasons and one incredible one. But what of that ‘06. Was it a fluke? These number suggest not:

Best single-season YPAs, ‘04-’07 (min. 60 att.)
1. Shawn Springs, Wash. -’04 4.2
2. Dre Bly, Detroit - ‘04 4.4
3. Champ Bailey, Denver - ‘06 4.7
3. - Fred Bennett, Houston - ‘07
 4.7
5. Sheldon Brown, Phil. - ‘04
 4.9

These are the only campaigns by every down corners the past four years to average under five yards per attempt. I think what we might be seeing are a general measure of a corner’s innate capabilities. These are the guys who get 1600s in the CB SATs. In Bailey’s case, he may not be the best cover corner year in and year out but his ‘06 shows that he’s more than able to play at an elite level.

In terms of using YPA as a heuristic, we can see that a YPA in the 4s signifies a sublime season, like a pitcher with an ERA around 2.00 or a hitter with an OPS above 1.300.

So Champ Bailey can be deemed the best corner in the game if we consider peak performance. But isn’t consistency the hallmark of a top player? Would you prefer a guy who can be incredible but plays that way only once a presidential administration, or somebody who can play very well year after year? Compare Bailey to the corners with the two best YPA averages since ‘04 and see how consistency ranks higher than flash:

Player-team 2004 2005 2006 2007 Avg.
1. Springs - Washington
 4.2 (1st) 5.5 (3rd) 6.2 (15th) 6.2 (15th) 5.5
2. Newman - Dallas
 5.8 (8th) 5.8 (7th) 7.1 (29th) 6.1 (14th) 6.2

To answer the question, I’m sure the Denver Broncos are happy to have Bailey on one edge of their defense, but if you ask Dallas fans, they’ll gladly take Terence Newman. He bounced back in ‘07, despite his plantar fascia injury and is a good bet to jump back into the top ten with more help in the Dallas secondary.

Another aspect of YPAs that deserves mention here is how they remake the term “shut down corner.” Fans take this term literally; when a blogger posted Dominique Rogers-Cromartie’s college stats, which showed opponnents completing less than 30% of passes in his direction, another blogger belittled those numbers, saying they didn’t reveal any special performance.

In fact, if an NFL corner posted Rogers-Cromartie’s line on a consistent basis he would get fast-tracked to Canton.

Stopping opponents 50% of the time appears to be the threshold for being considered a shutdown corner. In the last three years only 38 corners have achieved this — 9 in 2005, 17 in 2006 and 12 last season. Since shutdown connotes performance far above 50%, I think that the term be discarded or ignored; shut down corners simply don’t exist.

Only once in that span has a corner topped 60% in success percentage, that coming last year when the Raiders Nnamdi Asomugha posed a 62.9% success rate. Asomugha is the hardest corner to throw against, topping 50% in each of the last three years, the only cornerback to do so.

Might Asomugha then claim to be the best corner? Perhaps, but his YPAs indicate that while it’s hard to complete a throw against him, teams gain large chunks of yards when they do.

The YPA is hardly a perfect cornerback stat, but playing with YPA stats reveals a new cornerback world, one that elevates the steady over the flashy. Corners with 1600 SATs are impressive, but it’s the guys with scores in the 1200 and 1300s, the cornerback nerds who grind day-after-day and year-after-year who have the most success.

Written by Rafael Vela · Filed Under NFL | 12 Comments 

Who Is the Best Cover Corner?

July 7, 2008

This is the first in a series of pieces on the top cover cornerbacks and secondaries.

Who is the best NFL cover corner? Who has the best coverage unit around? The question is being kicked around a lot these days, with cornerbacks getting free agent contracts that rival those of quarterbacks for sheer dollars and bonuses.

I’ve come across several lists in recent weeks, all going off reputations, some earned, some not. BSR has decided to pursue these questions with the use of the largest database of corner coverage stats around. K.C. Joyner, the author of the Scientific Football books, will soon release Scientific Football 2008, the fourth edition of his series.

Joyner’s forte is breaking down the passing game, from offensive and defensive perspectives. His CB YPA will shortly become, in my opinion, shorthand for measuring a corner’s skills, in the same way that OPS has become the one stat that can best convey a baseball hitter’s skills. It’s easy to calculate and easy to understand. It shows how many yards a corner surrendered on average every time a pass was thrown to his man.

K.C. prints out a YPA ranking every year and in this year’s book has ranked the teams by tandem, calculating the average YPAs for the starting CB duos on each team.

What he has not yet done is compile YPAs over a longer span, say the last three or four years. When he learned I was putting such a spreadsheet together, he kindly forwarded his 2007 YPA rankings, which will not be published for several more weeks, and gave me permission to publish pieces from my calculated averages. BSR readers will therefore be the first to see these numbers. If you are not a regular Joyner reader, I highly recommend his ESPN columns and his books which can be ordered here.

The spread sheet raised as many questions as it answered. Although I have four years of data at my disposal, is it fair to omit a cornerback who has only played two or three years, but at a high level? What about a player who has missed a year due to injury?

In addition, what about players who have solid numbers but show a steady decline. Should I rate them above or below a player who has a similar number but whose averages are improving?

For now, I’ve decided to offer these breakdowns as a starting point for discussion, not as the last word in the debate over which players are best and which units are best. I’m going to offer two individual lists, one showing the best cornerbacks for the last four years and one for the last three years. The reason I’m pushing the data to be comprehensive is the generally inconsistent level of CB play from one year to the next.

It’s fairly routine to see a corner, even a good one, have two stellar years, then drop off a year and then bounce back strong again. For examples, look at the lines for Deshea Townsend and Ronde Barber on the top ten list below.

I’m sure there are many factors for a dropoff. A corner might be playing hurt. He may lose his confidence for a stretch of the season or an entire campaign. His pass rush might be weaker one given year. Whatever the case, there are not many corners in my sample who strung four strong years together. Even the better ones had a so-so year somewhere in the mix.

That said, I believe that a player must display consistency in order to be considered tops at his position. So my first list will, with one exception, include only those players who have posted numbers for the last four years.

Player-team 2004 2005 2006 2007 YPA Avg.
1. Springs - Washington
 4.2 5.5 6.2 6.2 5.5
2. Newman - Dallas
 5.8 5.8 7.1 6.1 6.2
4T. Townsend - Pittsburgh
 7.1 5.1 7.8 5.2 6.3
4T. Barber - Tampa Bay
 5.7 6.7 7.9 4.9 6.3
6T. Woodson - Green Bay
 7.0 * 5.3 7.2 6.5
6T. Lucas - Carolina 7.9 5.8 5.2 7.2 6.5
7. O’Neal - Cincinnati
 5.8 6.6 6.8 7.0 6.6
8. Smoot - Washington
 7.6 7.2 6.9 5.5 6.8
10T. Jammer - San Diego 7.8 7.5 6.2 5.9 6.9
10T. Asomugha - Oakland
 7.5 6.3 6.9 7.0 6.9

(*Charles Woodson did not get a rating in ‘05 because he was playing a rover position in Oakland’s system and did not qualify for the CB ratings.)

Some observations:

– The cornerback positon is incredibly unstable. You don’t think of corner as an attrition position, like running back, but there are only 40 players who had qualifying numbers each of the last four years. That’s just 1.25 per team. This is why cornerbacks who hit the open market make so much money. The demand for solid corners does not come close to meeting demand.

– Raise your hand if you considered Shawn Springs one of the top five corners in the game. I considered him for my top-of-my-head top ten, but he’s been the best YPA guy in the league the past four years.

– Raise both hands if you had Deshea Townsend in your top 20.

– There’s Terence Newman, Cowboys’ fans, parked at #2. His highest ranking in any given year has been 8th, but as you can see he’s been Mr. Steady. His 6.1 last year is even more impressive given his heel injury.

– In the what might have been category, check out Ken Lucas at 6th. The year he hit free agency he was rated higher by the Dallas scouting staff than Anthony Henry. Bill Parcells took the recommendation of Todd Bowles, who had coached Henry in Cleveland and who is now with the Tuna in Miami. Had Parcells pursued Lucas instead — Lucas did cost more — he might still be coaching.

– Notice the big names not on this list: Champ Bailey, Chris McAlister, Nate Clements, Asante Samuel? Inconsistency put them down the list. Bailey had one of the best years Joyner has ever recorded in ‘06, but it’s his only exceptional year the last four. He ranked in the bottom half in ‘04 and ‘05.

– Lastly, YPA tells us a lot, but don’t rush to judgments on guys who are on the list or are not. One fact that nags at me is that gambling, CBs, who Joyner calls “ball-hawks,” often have higher YPAs. Antonio Cromartie, for example, only had a 7.2 YPA last year, which is about league average. Guys like this will give up more intermediate and big throws in exchange for more picks. Conversely, CBs in cover two systems tend to have lower YPAs than they do when they play in more aggresive systems. Should we take the YPAs straight or weight them somewhat depending on a player’s personal style and scheme?

I’ll repeat, take this chart as a point of departure. Discuss.

Next: The top 10 CBs by YPA for the last three years.

Programming Note: I, like our Vice President, will be spending the next few days in an “undisclosed location.” I don’t know if his getaways involve a comely blonde, but mine will. I’ll see you folks again oh, Thursday.

Maybe.

Written by Rafael Vela · Filed Under NFL, Players | 95 Comments 

DISCLAIMER: This site and its contents are for informational and amusement purposes only. This site is NOT officially sponsored by, nor endorsed by the Dallas Cowboys football organization, its players, coaches, staff, or the National Football League. Nothing written anywhere within this site is intended to be perceived as the site being so sponsored or endorsed. All original work, articles and comment posted by Rafael Vela, Raul Villaronga or invited guest bloggers, however, are protected by applicable copyright laws. Comments written by posters visiting the site are voluntarily submitted to stimulate discussion and debate without the expectation of copyright protection on the part of those visiting posters. It is not the responsibility of this site or its authors to enforce the copyright protection of such comments posted by visitors to this site. The authors cannot assume any liability for actions taken in reliance on these articles...that would be just silly and Don Meredith (who also does not officially sponsor nor endorse this site, but we love him anyway) well, he would just laugh at you. Thank you.

Your Dallas Cowboys Blue and Silver Report is Digg proof thanks to caching by WP Super Cache!