Honestly, there’s not one player who doesn’t have something to prove at this year’s scouting combine. Along with how they perform at their Pro Days, the combine might as well be a job interview for draft-eligible prospects. But below are five guys who stand out as players who have a lot on the line this week in Indianapolis.

Ryan Mallett, QB, Arkansas
Reports have surfaced that Mallett bypassed entering the 2010 draft because he had a drug addiction problem. There are also concerns about his decision-making, his leadership abilities and whether or not he can stand up to pressure when the pocket collapses. Some have even labeled him the next Ryan Leaf, which is the kiss of death for any quarterback prospect. But even with all the questions that surround him, he’s 6-6 and 238 pounds, is an ideal pocket passer and has a cannon for a right arm. He won’t run or do any of the agility tests at the combine, but he will throw and interview with teams. I have no doubt that he’ll impress scouts with his physical skills, but he better put his best foot forward during interviews because teams will want to know what kind of character he has. Passing the mandatory drug test wouldn’t be a bad idea either.

Robert Quinn, DE/OLB, North Carolina
Quinn missed the entire 2010 season for his involvement in an agent scandal. If he played well last year (or played at all), he may have been the top pass rusher taken in this year’s draft and a surefire top 10 pick. But because of his suspension, he won’t be able to live on his physical skills alone. There’s no doubt that he has the talent to be better than Aldon Smith, Da’Quan Bowers, Cam Jordan and the rest of the defensive ends in his year’s class, but the time is now for him to start erasing doubts about his character.

Jon Baldwin, WR, Pitt
This is another player with tremendous athleticism but there are concerns about whether or not he’s a diva. He made comments suggesting that Pitt was trying to “disrupt” his draft stock because he was running a lot of deep routes where yards were “hard to come by.” Those comments raised red flags about his attitude and work ethic. But Baldwin could shine at the combine. He’s targeting a forty time in the 4.3s, with a 41-inch vertical leap and 20-plus reps of 225 pounds on the bench press. He’s a 6-5, 230-pound receiver who can fly. He’s a first round talent but if teams are worried about his attitude then he could fall past fellow wideout prospects Titus Young and/or Torrey Smith.

Ryan Williams, RB, Virginia Tech
Williams could really improve his draft stock this week in Indy. He was bothered by a hamstring injury last season and that led to a miserable 2010 campaign. But he recently ran a 4.41 forty with a 1.54 10-yard split, numbers sure to impress scouts if he can do it again at the combine. Assuming his hamstring is healed and he can run in the 4.4-range, he might catapult himself into the first round. He’s the type of slashing runner that scouts drool over because he has the short-area quickness and burst that teams covet. He needs a good showing at the combine though, because as of right now he’s living off the one great year he had in college (his freshman season back in 2009).

Nick Fairley, DT, Auburn
Fairley’s already a top-10 pick but if he wants to remind scouts of Ndamukong Suh, he’ll need to dominant at the combine. Suh had a terrific showing last year in Indianapolis and was a better overall prospect than Fairley, but because of the Panthers’ needs the former Auburn Tiger could go No. 1. (Unlike Suh, who “fell” to No. 2 because the Rams were in much need of a quarterback.) But he’ll have to convince team officials that he has the work ethic that should come along with being the top overall pick. He’s been called lazy in some reports and teams have concerns about his drive and motivation. Still, all the physical tools are there so he could light up the combine and secure his place at the top of the draft.