Wheelhouse said:
I think this is an outstanding post SSOG. 
Then again, a lot of your posts/replies are very results oriented and I know I'm not the only one that appreciates them. I'd like to see a further breakdown of what you posted here. Do you have a link to your findings or can you post more of the same regarding those numbers you uncovered? Thanks.
All data comes from
Football Outsiders- for my money, they're the best stat guys on the net. Obviously using stats to evaluate players has all sorts of problems (the FO editors are fond of saying that if Player X finishes #1, that doesn't mean he's the best, it means that Player X, getting the ball from QB X, who is being blocked for by Offensive Line X, while playing in the scheme of Offense X, is the best in the NFL). With that said, the really nice thing about their stats is that they're based off of pure success. A CB could give up 8 yards all day long on 3rd and 10 and he'd be considered one of the best, because every time the offense throws his way, they wind up punting. The only thing that matters is how much (or how little) a play does to result in points being put on the board. They also adjust all of their results based on the opposition (so shutting down Marvin Harrison counts way more heavily than shutting down Brandon Lloyd).Anyway, at the bottom of their
Team Defense page is a breakdown of how every defense does vs. specific receivers. Again, use caution when just taking these numbers as gospel, because there's all sorts of noise in the system. For instance, New York's pass defense looks great, but a lot of that has to do with having one of the best DE tandems in the league. Also, remember that most CBs (even the legendary Champ Bailey) don't always get matched up with the corresponding WR- when evaluating #1 CBs, I like to look at how a team did against #1s *AND* #2s, since very rarely will you get a top CB matched up against a #3 WR or an RB (although Champ plays against the TE sometime, which adds some noise, as far as I can tell he's the only one who has done that with any regularity).
Anyway, for the most part, the stats make sense with what he intuitively know. There are only 8 teams that were in the top 50% of the league against both #1s and #2s: Baltimore, Jacksonville, Green Bay, Denver, Philadelphia, NYG, Dallas, and San Fran. For the most part, this makes sense, since a lot of those teams are really well known for stellar CB play (Balt, Jax, GB, Den, Philly, and Dal). The two puzzling presences on the list are NYG and San Fran, and NYG is simple enough to explain. I have no idea what the deal was with San Fran. Some people might see their presence and say that it invalidates the entire list, but personally, I just think that sometimes, weird stuff happens.
Looking at the teams that were in the top 10 against one receiver and the bottom 10 against another, you have Detroit (7th, 32nd), Oakland (2nd, 24th), Buf (3rd, 27th), New England (6th, 29th), Kansas City (4th, 25th), Cincy (24th, 9th), and Houston (26th, 8th). Five of the 7 were top-10 against #1s and bottom-10 against #2s... and four of those five were known as teams with stellar top CBs and nothing behind them (Bly, Asomugha, Clements, Samuels), while KC is the oddball on the list (possibly an indication that Law is underrated, or that Surtain is still better than we think? I don't know, I didn't pay attention enough to KC's defense to see who usually handled which coverage responsibilities). I don't really know how to explain Cincinnati or Houston, I'd have to think about that a bit more. My initial guess is that it's something of a statistical fluke resulting from the CBs catching more INTs against the #2 WR than the #1 WR, but maybe someone who's a bigger fan of those teams can help.
Like I said, I'd really just recommend poking around a lot and looking for anything that looks interesting or like an aberration. A lot of people really disparage stats and say that they're no replacement for using your own eyes. I really agree that nothing beats actually watching for yourself, but statistics can do a wonderful job of picking up on trends far before you would, as well as focusing your attention on the stuff that you should really be paying attention to. For instance, absurd statistics are what got me paying attention to Lee Evans and MJD in the first place, and I certainly haven't regretted that yet.