At times, I believe, the Broncos have used Bailey to cover Gonzalez and Gates. Obviously, this might make some sense. Did this happen much last year and did it affect his %covering the #1 wr?

While I'm sure Denver had something to do with it, couldn't it just be teams making sure their #1 WRs avoid Champ Bailey?

(congrats on getting the bbok done)
Assuming a healthy Ellis Hobbs will win the left side cornerback position, I don't think we'll see a major drop off from losing Samuel.
Hobbes' cover skills as the right corner were (in my mind) at least as good as Samuel's when he played the right side in previous years.

The area where Samuel seemed to have had an advantage over Hobbes is his ability to jump short routes, and he liked to hit a little more. Also, history seems to show that the Pats left corner gets more interceptions, although there are probably many variable reasons for it.

The overall average numbers for both corners was maddening to me last year, where it seemed they consistently gave too much cushion and too many underneath passes to receivers.

Ultimately, I think Eagles fans will be very happy with Samuel, and Pats fans will be happy keeping Hobbes. The concern should be about what will happen in the newly vacated spot with Samuel and Randall Gay gone, and the replacement of the old defensive backs coach with Dom Capers.

1 - I do remember Champ Bailey covering Antonio Gates in the red zone during one of the divisional games the year before last. Bailey thought he had the pick and then Gates just bumped him out of the way and caught the TD. It didn't seem like a particularly effective strategy to me.

RE4: I believe you are incorrect. In many observations (including a mailbag at football outsiders) two years ago Champ was not credited as giving up Any touchdowns. Three years ago he gave up some, as well as last year. However, last year Bailey was not covering "dominant" TEs like he was before, atleast not to my recollection.

5 - But as I recall, and I could be way off here, that mailbag was pointing out the inherent absurdity of the CBS commentators claiming that Bailey hadn't given up any touchdowns. Or maybe it was something else like when they claimed that Bailey had only allowed 4 (or some utterly impossible number like that) catches through whatever point in the season that it was. In any case, I remember the CBS commentator saying something completely insane about Champ Bailey and, even as a huge Champ fan, thinking "that's completely false." and then reading an FO article that pointed out that what the commentator said had been completely false. Grr, I wish I could remember even one detail about this, but I just can't.

Couldn't Bailey covering number 2 receivers be a strategy to slide the coverage completely away from him?

I mean, most number 2s in the NFL can't beat Bailey, and the Broncos must feel they can leave him literally on an island and scheme around number 1 receivers.

Re 8:

It might have been what they thought, but the results speak for themselves. 9.5% DVOA, ranked 19th in pass defense.

Anyways I remember I lot of discussion about how Denver was running a zone scheme instead of man-to-man.

Would most people agree that Champ Bailey is one of the better defenders right now? Would most people also agree that EVENTUALLY a decent WR will get open (meaning that complete lack of pressure on the QB will allow for a completion)? Hence, "shutdown" is a limited and relative expression.

I believe the Patriots tend to play something like a zone much of the time, allowing for more teams to scheme away from top coverage. If a CB's strength is (comparative) "shutdown", man coverage then playing lots of zone may not be the best use of that individual's strengths. Of course, there are 10 other people playing defense and you may have to scheme away from your weaknesses rather than towards your strengths.

We're not going to have any more fiasco's this year with PFP'08? I ended up having to buy 2 copies since Amazon shipped theirs something like a week late last season. I'm not really complaining about that... but just wondering...

re 9:

The Broncos poor pass defense can't be placed squarely on the cornerbacks - John Lynch isn't great in coverage anymore, and he's apparently the best safety on the team. The defensive ends are a liability at best. 19th in pass coverage isn't bad as a team defense.

And against number 2 receivers, they were 8th in the league. Against number 1 receivers, they were 17th - not great, but not bad. So, again. They could have been seeking to leave Champ Bailey alone, and scheme around the weaknesses at safety and defensive end.

Aaron, are the raw numbers for each team going to be in the book -- the percentage of times each cornerback covered a No. 1, No. 2 or other receiver, and the stats for each (including attempts, etc.)?

Also, have you ever thought of adjusting defensive backs' stats for the number of defensive snaps played and/or the number of pass plays when they're on the field? A cornerback being targeted 80 times out of 500 passes is much different from a cornerback being targeted 60 times out of 200 passes.

How do Champ Bailey's numbers work out if you consider Gonzalez and Gates as #1 WRs? I can't help but think that affects his stats. I mean, the Chargers' #1 receiver is named The Guy In Single Coverage: Jackson, Chambers, Gates, Tomlinson... it's bad news all around. The Chiefs have sort of a deficit at WR, but they've got very good starters TE and RB positions.

OT: Can Eagles fans fill me in on Scott Cohen, the head of pro personnel for the last 7-8 years? The Jets just hired him as "assistant GM" and I'm just wondering what Cohen actually did in Philly.

Re #4: 1 - I do remember Champ Bailey covering Antonio Gates in the red zone during one of the divisional games the year before last. Bailey thought he had the pick and then Gates just bumped him out of the way and caught the TD. It didn’t seem like a particularly effective strategy to me.

I know which play you're talking about. On the play in question, Bailey was actually covering a different receiver, but left his man early when he saw that Gates was going to be the target, raced across a sizable stretch of field, and arrived just in time to almost make a play.

He spent more time in coverage of Gates and Gonzo in 2004 and 2005, and the numbers there speak for themselves. In 8 games against Denver, Gates and Gonzo combined for 27/280/1 (or about 3.4/35/.1 per game). Only once did they score (a TD by Gonzo), and only once did they break 50 yards (an 80 yard game by Gates). Against the rest of the league during that span, Gates and Gonzo combined to average 6.0/73/.6 per game with 31 TDs and 42 50+ yard games.

"
(Denver with Champ Bailey is ranked LAST, which shows you what a completely screwed up defensive strategy they had in Denver last year.)"

With Dre Bly on the other side, I'm of the oppinion that Denver is the team that LEAST needs to move CBs around.

Question for Aaron, etc. Do you guys have any numbers on how often Hobbs/Samuel had Harrison behind them?

I seem to remember a lot of plays where Hobbs would look like he was handing off coverage, and then there was no one behind him, or the next safety was 20 yards back.

In my oppinion, Sanders is a better all around safety that Harrison at this point (except for blitzing), and Merriweather is most certainly better in coverage.

This makes a lot of sense, actually. If your #1 CB can't shut down their #1 WR, but can shut down their #2, you might as well put him alone on #2 and double the #1 with two schlubs who between them have enough ability rather than be overmatched against both #1 and #2 WRs.

20: Except the math isn't that simple. In a linear programming (knapsack) problem, given three objects of value 2, 3, and 4, and two knapsacks which require values 4 and 5, it makes sense to use your best object in your 4 knapsack, while combining your inferior objects to fill your 5 knapsack. But the function of success S for cornerback C covering receiver R is NOT a binary defined as S(C,R) = C >= R. Creating such a function (or even defining its type!) is a mammoth task, and this is a perfect example of why: if your #1 CB is covering a #2 WR to allow a true double team on the #1 WR, he has to be very, very careful not to get burned, because there's no safety to prevent a TD. This is going to influence his coverage, possibly causing him to allow more short passes and grab fewer interceptions.

This doesn't mean, of course, that this is a bad strategy -- just that the analysis is quite complex. Even after calculating how effective the strategy is, calculating when it's appropriate is non-trivial. Putting all that together would make a really interesting piece of research. If only there was a group of people who investigated aspects of football by looking at the numbers and published their analyses...

I also remember Hobbs getting burned a lot not because he sucked, but because the rest of the coverage was messed.

He also has a bad public image because, like Bailey in the example above, he sometimes sees a gap in coverage and tries to fix it, but gets there just in time to get burned.

Thats what happened against PIT this year, when that RB caught a TD pass-- Hobbs was across the field and ran his butt over there, just in time to get a snapshot of him getting burned when it wasn't his man.

And Harrison played as a LB a lot of the time... I think they are going to a 3 Safety package with him as a hybrid S/LB. It will be the nickel package, which they will use like 40% of the time.

I like Hobbs and think he will be fine. Also like the rookies, they are looking good from what I've heard.

There is a pretty big flaw in the premises of this article:

The answer is that top cornerbacks cover the other team’s top receivers much, much less than people think. In the book, we have a stat called “CB1 on WR1″ that measures the percentage passes listed with the top corner in coverage where the top corner is covering the other team’s number-one wide receiver.

The stat in question does not measure how often CB1 covers WR1, it measure how many times during the game the throw goes there when CB1 is covering WR1.

WR1 gets thrown to something like 8 times a game out of 70 or so plays, isn't it likely that an intelligent QB probably threw to WR1 a disproportionate amount of the time they are covered by CB2 and CB3?

Maybe of the 70 plays, CB1 was in coverage for 50 plays. How many times are audibles from run to pass or pass to run called there?

Throwing Audibles out, doesn't it seem likely that a QB might throw to the primary receiver a larger percentage of the time they are covered by CB2 or CB3? Suppose on 25 pass plays, CB1 is in coverage on WR1 20 times and he gets thrown to 5 times. On the other 5 pass plays, WR1 might get thrown 3 passes. That would show up as 8 passes, 5 with CB1 in coverage, but it was really 30 pass plays, 25 with CB1 in coverage. Using passes and not pass plays may seriously distort the data.

If the word "passes" above was really "pass plays" from charting data and not "passes" from play by play, then some of my points are moot, but everyone who missed the typo loses one point.