NFL Combine 2012: Defensive Back Prospects Who Can't Afford a Poor Showing

In a loaded NFL draft at the defensive back position (mainly cornerbacks), those who stand out will shine even brighter, and those who flop will be just as exposed but in a disappointing light.

And whether it's because the following defensive backs need to just respond after a poor outing, are looking to increase draft stock and/or are undersized, a poor showing at the combine will be detrimental to them this spring.

Alfonzo Dennard, Nebraska

He has all the tools to be a shutdown corner in the NFL: Size, toughness, physicality, tackling and ball awareness.

Unfortunately, Nebrask's Alfonzo Dennard went from a legit top 15 pick to a potential early/mid second-rounder after not impressing during the Senior Bowl. Playing a lot of press/bump-n-run coverage with the Cornhuskers, Dennard failed to display he can play off in soft coverage.

Although his strengths are at getting physical with a receiver, it won't fly every down in the pros. For one, he's simply putting himself at too much risk in getting beat early on a play, thus leaving no chance for a recovery.

In short, having consistent tendencies will expose a player and unless Dennard proves otherwise at the combine, he's going to drop even further.

Brandon Boykin, Georgia

Georgia' Brandon Boykin had a strong career and put on a solid display at the Senior Bowl. The man has all the tangibles and intangible you want in a corner, but he still remains a mid-round pick.

To that end, include Boykin being undersized at 5'9", 185 pounds and a weak performance at the combine will drop him significantly. There's no doubt that Boykin can run with and catch up if beat on fast NFL receivers.

But, it's getting overpowered by the much taller and stronger targets that need not worry about out-maneuvering him with their feet. Even the smaller slot receivers can take advantage, as Boykin isn't used to playing with outside leverage directly lined over an inside receiver.

Still, Boykin does have great awareness, isn't afraid to get physical and has the instincts to be a great playmaker. As long as Boykin doesn't allow his size to get exposed, he will remain a top cornerback prospect.

Trenton Robinson, Michigan State

At 5'10", 195 pounds, Trenton Robinson is built like a corner (slightly bigger than Boykin), quick and has good ball awareness. Still, being that he's a little undersized for a safety and currently a projected late fourth/early fifth-rounder, Robinson has a lot of proving to do.

In the pros, man coverage will work against slot receivers and receiving running backs, but not much else. And since Robinson is more of a zone defender, sitting back deep will be a defense's best option for him.

Another downfall is that the Big Ten isn't known for being a pass-oriented conference. So, compared to other safeties such as Oklahoma State's Markelle Martin, his overall pass defense needs more evaluation.

As for the combine, watch for his change of direction, where he catches the ball in interception drills (highest point or waits on it) and his back pedal from a rolled down position. Already a mid-rounder, a poor showing would drop him into Round 6, if not worse.

John Rozum on Twitter.