The 40 time really seems rather useless as a measure of effective CB play. I really wish the Pats wouldn't use this as a defining metric. Lets take a look at the 40 times of the top CB duo in the game today.
Brandon Browner - 4.63 (prob why he went undrafted)
Richard Sherman - 4.54 (prob why he lasted until the 5th rd)
Another one worth mentioning is Brent Grimes - 4.55 (also undrafted FA)
Why does anyone care if a CB can run in a straight line really fast? That skill is only put to use if the CB is beat deep because of poor route judgement. They could have a blazing 40 but if they can't get their hips turned quickly enough they could be slower on the field than someone running a 4.7 40.
Just read that link upthread and wonder if there has been a shift in the game over the last couple years that allows bigger slower CB's to be more successful now as opposed to the 10yrs during that study. It is possible that the 3 I listed are simply anomalies but I wonder if their is a fundamental change that is now allowing more physical albeit slower CBs to be successful. Perhaps with teams really emphasizing the pass rush they aren't asking their CBs to cover deep like they might have a few years back?
I don't know the answer but it is probably worth investigating why suddenly CBs with +4.5 speed are succeeding when historically that has not been the case. Perhaps there is some value in the draft or even UDFA market by targeting some of these CB's.
First I doubt the patriots use the 40 as a "defining metric." Like virtually everybody in the leagye, they draft fast corners.
As to why a couple of slower corners have done well, the most obvious point is that Browner, Carr and Sherman are big dudes. Browner and Sherman are 6'3' or 6'4' and Carr is 6'0", 205ish. The refs are generally letting corners be a lot more physical lately so this favors big powerful guys.
A second thing to keep in mind is that the 40 yard dash only tells you what a fresh, rested athlete does. I'd be a lot more interested in what a corner can run in pads his 10th 40 yard dash in a half hour, and I wouldn't be surprised to learn that some of the corners who have outplayed their draft status are players with great functional speed and endurance.
Two other points:
*Published 40 times are often a little sketchy--they're not always apples to apples comparisons as the timing methods at the combine shift a little from year to year, and pro day times are just kind of made up.
*I'm sure player speeds change after they've been in the pros a few years. Repeated contact can slow you down, conditioning, strength training, additional physical maturity and increased flexibility can make you faster, but certainly some players hit a point where they get so big they lose speed (Mayo looks like a case in point).
Edited by Shelterdog, 28 January 2013 - 09:02 AM.