Dan Pompei

The draft stock of players at any position can dip, plummet and twist based on what happens at the NFL combine in Indianapolis. But traditionally, it seems more cornerbacks are affected than players at any other position.

Why cornerbacks?

Speed accounts for a greater percentage of a cornerback’s value than it does for other players on the field. If a cornerback can’t run, he has only so much draft value. And a cornerback’s speed isn’t as easy to gauge on tape as the speed of a wide receiver, for instance.

In fact, cornerbacks are the most difficult players to evaluate on tape. You can watch a whole game and not see a cornerback challenged. And a premier corner might only see a handful of deep balls in an entire college season.

Corners are not involved in many plays, so the opportunities to evaluate them are fewer than for linemen, quarterbacks, running backs, tight ends and linebackers. And even though receivers don’t always get the ball, they still are evaluated on routes and blocking.

A college cornerback might play very well on tape, but that doesn’t mean a talent evaluator can be certain the cornerback will play very well in the NFL. The talent level of the receiver the cornerback is competing against has to be factored into the equation.

What you can learn from tape is if the corner has instincts, ball skills and the willingness and ability to hit and tackle. What you can learn from the workout is if he can run fast, change directions quickly, and jump (which can offset height disadvantages).

Cornerbacks in the past have turned in some of the most talked-about combine workouts. Deion Sanders famously ran the fastest combine 40 ever — a 4.27 in 1989. Every year since his time has gotten faster.

In 2005, Fabian Washington became a first-round pick mostly as a result of his 4.29 40-yard dash at the combine (trust me, it wasn’t his tape). Last year, Chris Houston boosted his stock with a 4.32 40-yard dash.

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The combine also helps scouts separate cornerbacks because it allows them to see corners use techniques they played infrequently, if at all, in college. Houston, for instance, was a press corner at Arkansas, so scouts wanted to see him play off in drills at the combine.

Some corners only play zone in college, and scouts want to see them play man. Some are hardly ever asked to backpedal, instead being coached to turn and run with receivers. Combine drills help coaches envision what a cornerback would look like in their specific scheme.

“There can be a bigger swing in the stock of guys like that,” said former Texans general manager Charley Casserly, now a CBS contributor.

One cornerback who has a lot riding on his combine workout is Aqib Talib of Kansas. The junior’s tape is pretty impressive, but there are some lapses in his play that have left scouts wondering if he’s fast enough. “If he runs an impressive 40, he could be a top 10 pick,” one NFL college scouting director said. “A bad 40 and he could drop to the second round.”

Other players who are most affected by workouts are tight ends (they often aren’t utilized much in college), wide receivers (there are so many receiver prospects that workouts help teams separate them) and linebackers (athleticism is king for them).

Players who are least affected by workouts are quarterbacks, offensive linemen and kickers and punters.

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