As much as the NFL Scouting Combine is about numbers -- a player's time in the 40, his vertical leap, his bench-press reps -- it's really an event that comes down to history. More than anything, what teams are trying to figure out is how prospects measure up in specific workouts that, based on history, have been important indicators for success or failure in the NFL.
Here's an example to illustrate this point. Let's say there's a good quarterback prospect out there, and he's got small hands that measure under nine inches. History tells us that we've had only one quarterback since 1983 whose hands measured under nine inches who started in the NFL. That's one quarterback in more than 30 years -- would you want to buck those odds?
There's a reason behind every drill that's performed at the combine, and every position (there's 13 of them) has its own specific set of drills that are important. But the main goal behind these drills is the same -- you're trying to find a way to separate large groups of players who look alike on the surface, and you accomplish this by comparing them in drills that, for years, have been good measuring sticks for the NFL.
Let's focus on cornerbacks. People have begun to emphasize the size of cornerbacks recently, especially because of the success of the Seahawks' big corners. But based on past history, height has not been a major contributing factor to success or failure in the NFL. There have been successful cornerbacks who were 6-foot-2, and there have been successful cornerbacks who were 5-10.
There are three drills that have been significant indicators for cornerbacks: the 40-yard dash, the three-cone drill and the broad jump.
Obviously, these aren't the only drills that are considered at the position, and there are a lot of other factors to consider -- for example, a player might have a poor 40 but an exceptional 10-yard time, which tells you he has great burst -- but historically for cornerbacks the three mentioned above are the most important.
Straight-line speed is the No. 1 attribute for success when it comes to corners. The reason is simple: A corner who can't keep up with a wide receiver is going to be in trouble. Now, there are guys who have a special feel for the ball, or guys who know how to break on the ball and so forth, but when a team tries to cover a 4.4 wide receiver with a 4.65 cornerback and doesn't get a great pass rush, chances are it's going to give up seven points.
There are other key drills for corners (more on this below), but none is tied to a higher percentage of success than the 40. Based on history, you want your corners to post a time of 4.5 or under.
Notable 40 times from past combines:
» Darrelle Revis, 2007: 4.39
» Leon Hall, 2007: 4.39
» Dominique Rodgers-Cromartie, 2008: 4.33
» Chris Houston, 2007: 4.32
The second drill of significance for corners is the three-cone drill. This measures a player's ability to change directions, as well as his burst and his ability to bend and turn. It shows you whether a guy is a good athlete, but also tells you if he's a quick thinker. These are all important skills for a position that requires lots of change of direction, covering slant routes, out routes, fly routes and so forth. Guys who run the drill in under 7.10 are almost a cinch to make it in the NFL.
In the 1997 draft, the Carolina Panthers made a bit of a surprise pick by taking Nebraska cornerback Mike Minter in the second round. Minter didn't run a strong 40, but he stood out by ranking in the top percentile in another important CB drill, putting up an excellent time in the three-cone drill, at about 6.57 seconds. Minter ended up playing in the NFL for nearly a decade.
Notable three-cone drill times from past combines:
»*Chris Houston, 2007:* 6.94
» Brandon Carr, 2008: 6.80
» Darrelle Revis, 2007: 6.56
» Leon Hall, 2007: 6.50
The third important drill for corners is the broad jump. Now you might be wondering why teams would emphasize this drill for cornerbacks. Again, it has to do with history. About 72 percent of starting cornerbacks in the league averaged a broad jump of 10-foot-2 or more. (Ellis Hobbs had the best that I could track, at 11-foot-3.)
Notable broad jumps from past combines:
» Chris Houston, 2007: 10-foot-2
» Darrelle Revis, 2007: 10-foot-5
» Fabian Washington, 2005: 10-foot-9
» Ellis Hobbs, 2005: 11-foot-3
In the 2005 draft, the Raiders traded up to the No. 23 pick and drafted Fabian Washington, a player who was not really thought of as a first-round talent but who did very well at the combine. I'm sure one of the reasons the Raiders moved up to get him was because he did so well in all three of these CB drills, and so it brought him to the forefront.
That's kind of what the combine is all about for NFL teams. They're trying to find a more thorough, definitive way to evaluate players based on skills that have been important to success in the past. Combine drills are an additional piece of information that's weighed in along with a player's production on the field, among other things. It's an attempt to make projections with the help of what we know from history.