The Phinsider

In terms of stock for college football prospects, the NFL Combine giveth and the NFL Combine taketh away. And while some prospects next weekend are going to light up Lucas Oil Stadium like a Christmas tree, others might see their draft stock slip a bit due to a sub-par 40 yard dash time, height and/or weight results that come in below projected totals, poor interviews, etc. The reasons for falling draft stock are sometimes overblown (something Aaron Rodgers would gladly attest to, I am sure), and sometimes they are very much justified (remember when people thought the Dolphins were going to take Vernon Gholston with the first overall pick in 2008?). In the end, draft stock only tells part of a player's story, but it's a vital part of the process used to justify whether a particular draft pick is a reach or a value selection; a need or simply a best-player-available approach; and, sometimes, a success or a failure.

Here's a look at three big-name prospects who might have some work to do after next weekend.

Martin was viewed as the No. 2 tackle prospect in the 2012 NFL Draft through must of last season, but plodding footwork and average output in pass protection in 2011 reduced him to potentially being the No.4 tackle in this draft class. For Martin to nudge out Ohio State's Mike Adams for the No. 3 overall tackle spot, he'll have to show scouts he is comfortable sliding and mirroring pass-rushers and nimble enough to recover when initially beaten with moves to the inside or around the edge. If so, Martin will be a top 15 pick, because he's arguably the best road-grading tackle in this draft. If he struggles with Combine drills, he'll likely be a late first-round pick.

2) Alshon Jeffery, WR South Carolina

Alshon Jeffery has former USC Trojan Mike Williams to thank for being included on this list. Jeffery is a big-bodied, physical wideout with phenomenal mitts and elite ball skills, but his weight is ... well, up there for a wide receiver. And because Jeffery's speed is marginal at best, it's unlikely he'll be able to demonstrate any semblance of separation speed during Combine drills unless he chooses to cut weight. Bottom line, Jeffery needs to weigh in under 235 pounds and run in the 4.5s to warrant a late 1/early 2 selection. Otherwise, he'll be viewed as a candidate for the Williams/LenDale White school of eating.

And to be fair, the 40 yard dash will also greatly affect the draft stock of Notre Dame's Michael Floyd. Floyd cut a bit of weight this season and looked much more explosive for the effort, but he'll need to run in the mid-4.5 range if he wants to hold off Baylor's Kendall Wright as the No.2 wideout prospect in the 2012 draft. Wright's 40 time will almost certainly be ridiculous (likely in the 4.3s), so Floyd's work will be cut out for him.

3) Dre Kirkpatrick, CB Alabama

This one could go either way, since Kirkpatrick's possesses some elite physical attributes for the cornerback position. He has outstanding height (6'2") and arm length, and he's expected to run in the mid-4.4 range. He's also a fierce run defender and a big-time hitter in the Ronnie Lott mold. However, Kirkpatrick's man coverage abilities are still very much in question, so scouts will be on the lookout for any sloppy footing in his backpedal or tightness in his hips. If his technical skills check out in Indianapolis, Kirkpatrick will potentially lock up the No.2 cornerback spot in this draft. If he struggles during drills, then he'll likely be leapfrogged by North Alabama's Janoris Jenkins (who is the polar opposite of Kirkpatrick--short stature, but simply brilliant in man coverage).