Combine players with most to prove

— -- Every year, the NFL scouting combine plays a determining factor in how prospects are viewed by NFL teams, but some prospects have more on the line than others in Indianapolis this week. This includes players with the most to prove and/or gain during the measurements and athletic testing portions of the weeks, players with the most riding on their interview sessions, players with the most riding on their medical testing and players most likely to post the fastest 40-yard dash times (and that's not even taking into account that putting up a fast time could land players a Porsche this year).

Let's take a look at the players in each group:

Five players with the most on the line during workouts:

Kevin White, WR, West Virginia: The big thing for White is his 40-yard dash. On tape, he has almost everything you look for in a wide receiver prospect: He has very good size (6-foot-3, 211 pounds), he has outstanding ball skills, and he put up exceptional numbers -- and did so against very good competition (including 35 combined catches versus Alabama, Oklahoma and Texas). The only issue is on tape he doesn't appear to have elite, top-end speed. He is already a likely top-20 pick and the second-ranked receiver on our board, but if he can run in the 4.4s, he could be the first receiver drafted and go in the top 10.

Arik Armstead, DE, Oregon:  His production with the Ducks wasn't great (just 2.5 sacks in 2014), but his playing as a 5-technique defensive end in a 3-4 scheme is partially to blame. For teams to be comfortable taking him early in the first round, they need to feel confident he has the physical tools to produce more sacks at the NFL level, and that means he'll have to put on a show in the athletic testing -- which I think he'll be able to do. Armstead, a former basketball player, is a phenomenal athlete at 6-foot-7, 285 pounds with excellent strength and quickness. He needs to prove it to NFL decision-makers, from his running and jumping to the bag drills.

Danielle Hunter, DE, LSU: Hunter is similar to Armstead in that he is an elite athlete but wasn't particularly productive this season (just 1.5 sacks), and he has a big opportunity to impress NFL teams with his performance in the drills. His effort, ability to stuff the run and overall skillset are all there, but he simply has too much length and speed to not get home against the quarterback more often than he did this season. He needs to show that his raw tools are all there with his flexibility testing, change-of-direction skills in the three-cone drill and shuttle runs, and powerful hands in the bag drills. He needs coaches to come away from Indy feeling confident they can develop him into an effective NFL pass-rusher.

Owamagbe Odighizuwa, DE, UCLA: He looks the part -- he's well-built, which was evident at the Senior Bowl -- and should perform extremely well in Indy to improve his draft stock. He plays hard, has a great work ethic and should interview very well, and he is very good against the run, but he could really improve his stock by exceeding expectations in terms of his speed and change-of-direction testing. He also has a lot riding on his medical exam, as he's had multiple surgeries in his career and missed the entire 2013 season.

Jordan Phillips, DT, Oklahoma: He is just a freak in terms of his combination of size and athleticism -- he can do a standing backflip at 6-foot-5, 334 pounds. His effort is very up and down; teams are going to have to get to the bottom of his passion for the game in his interviews. He also dealt with a back injury, which could scare off some NFL decision-makers. That's why it's very important he meet the expectations teams are going to have for him as an athlete. He might not put up the numbers Dontari Poe did during his combine -- 44 bench reps and a 4.98 40-yard dash at 6-foot-3, 346 pounds, which is just ridiculous -- but he has a chance to be in the same ballpark. Phillips isn't quite as strong, but he might beat Poe with some of his times.

Five players with the most riding on their interviews:

Editor's note: A.J. Johnson was removed from this list following news the league withdrew its invitation to the former Tennessee linebacker.

Jameis Winston, QB, Florida State: The question NFL teams -- likely those picking at the very top of the draft -- are going to have to answer is this: Can Winston be trusted? From an on-field standpoint, he's No. 1 overall pick material and the best quarterback prospect I've evaluated in the past 10 years, besides Andrew Luck. But teams are going to dig into his past behavioral issues, most notably the Dec. 7, 2012, incident for which he was accused of sexual assault (the state attorney ultimately decided not to press charges due to a lack of evidence) and an incident in the spring of 2014 in which he was issued a civil citation for walking out of a supermarket without paying for $32 worth of crab legs and crawfish. Psychologists will be studying his interviews closely. How sincere are his answers? What is he doing to improve off the field? Is he remorseful? Does he understand his behavior needs to improve?

Dorial Green-Beckham, WR, Oklahoma: He might be the most physically gifted wide receiver in this class (6-foot-5, 225 pounds, excellent speed), and even though he's raw and has had off-field issues, he still could be a late first-round pick. What he's going to have to answer for are two marijuana-related charges while at Missouri and an incident this past offseason that caused him to be investigated for burglary and assault and subsequently kicked off the team. (He never played a down for Oklahoma; he sat out the past season due to NCAA transfer rules.)

Marcus Peters, CB, Washington: If he isn't the first cornerback taken in 2015, it will be a direct result of his behavioral issues because he is the clear-cut No. 1 corner in this class. But teams are going to have to really look into his maturity and accountability, as he has had a laundry list of off-field incidents: a failed drug test in 2011, an academic suspension in 2014, and several suspensions and ultimate dismissal from the program in 2014 related to showing up late or missing practices and throwing a tantrum with coaches on the sideline of a game. He's talked openly about taking responsibility for his past behavior and is a fiery competitor on the field who loves the game, but teams are going to need to be convinced they can trust him.

Frank Clark, DE, Michigan: He was dismissed from the Michigan program in November after being arrested on misdemeanor domestic violence and assault charges and has had previous run-ins with the law, including a second-degree home invasion charge in the summer of 2012 (he pleaded guilty to a felony charge and received probation). We had a fifth-round grade on him entering the season, but he's a free-agent prospect now.

Five players with the most riding on medical testing:

Todd Gurley, RB, Georgia: He's a top-15 type of talent, but his durability is a major concern when projecting his long-term success in the NFL. He suffered a season-ending ACL tear in November, and he missed three games in 2013 due to an ankle injury that clearly bothered him after he returned to the field. He runs behind his pads and usually delivers the blow, but he does take some heavy body blows when he fails to dip his shoulder before contact. The good news: He finished his college career with just 555 carries.

Duke Johnson, RB, Miami: He's undersized (5-foot-9, 206 pounds), and even though he started all 13 games in 2014, he dealt with some injuries during his Miami career. He suffered a season-ending ankle injury in 2013, has dealt with concussion-like symptoms and has a history of migraines. He's a very explosive player, but durability concerns could hurt his draft stock.

B.J. Catalon, RB, TCU: He is a fast and versatile back who warrants Day 3 consideration because of his talent, but his history with concussions (the most recent was Nov. 1, 2014, against West Virginia) could scare teams away. His medical testing will be important as a result.

Stefon Diggs, WR, Maryland: Diggs is another explosive player who has been limited in his career, due to injuries. He missed a game in 2012 with an ankle injury, suffered a season-ending fractured right fibula in 2013 and sustained a lacerated kidney in 2014.

Lorenzo Mauldin, DE, Louisville: He missed all of 2014 spring practice while recovering from a shoulder injury, then dealt with a nagging hamstring injury all season and missed the Boston College game as a result. He missed two games in 2012 with a sprained knee and partially torn MCL. He is a potential Day 2 pick in a deep group of pass-rushers, but he'll need to check out medically first.

Who will run the fastest 40-yard dash?

The 40-yard dash is typically the most watched drill at every year's combine. Here is a look at the fastest 40-yard dash times of the past decade:

Who are the top candidates to run this year's fastest 40-yard dash? My money would be on one of these four:

Phillip Dorsett, WR, Miami: He was the fastest player at the Senior Bowl, and it wasn't all that close. He really turned some heads with his speed. His production doesn't quite match up to that of many of the other top wide receivers in this class, but a great 40 time and good all-around workout could push him ahead of several of those guys on teams' draft boards.

Sammie Coates, WR, Auburn: He has very good size, length and straight-line speed and flashes the ability to make big plays in the vertical passing game, having hauled in some unbelievably acrobatic catches. But his ball skills overall are marginal -- the worst of any I've studied so far in this year's class -- and he's wildly inconsistent as a route-runner. He'll need a great 40 time to be a first-round consideration.

Mario Alford, WR, West Virginia: He's a one-trick pony, but if you're going to have just one, his is the one to have. He runs "9 routes" -- and runs them at a really fast pace. He supposedly runs in the low-4.3 range in the 40 and should be one of the combine's fastest performers.

Devin Smith, WR, Ohio State: He's a track guy, having participated in the high jump and 4x100-meter relay for the Buckeyes, and his speed translates well to the football field. I think he was a bit overlooked, in terms of how important he was to OSU's success this season, as he was the best downfield threat in college football. He has a chance to run in the 4.2 range.

Combine snubs

Here's a list of the 10 highest graded players on our draft board who were not invited to the combine:

Antoine Everett, G, McNeese State (Grade: 72)
Xavier Williams, DT, Northern Iowa (56)
Henry Coley, ILB, Virginia (54)
Deontay Greenberry, WR, Houston (54)
C.J. Olaniyan, DE, Penn State (47)
Patrick Miller, OT, Auburn (46)
Chris Harper, WR, California (44)
Aundrey Walker, G, USC (44)
Deion Barnes, DE, Penn State (42)
Kaleb Eulls, DT, Mississippi State (42)