For those invited and participating in the 2015 NFL Combine, what matters? What’s the most important thing to watch out for? They’re all talented and they all have elite skills, but there are keys that every scout and GM will be looking at. Here’s what each prospect has to prove … 

1. Leonard Williams, USC 6-5, 300
Has he harnessed his skills yet? There’s no questioning his combination of size, speed and upside, but he’s still in need of some molding. Is he ready to be a franchise-making defender? Anyone who takes him will be expecting Pro Bowls – plural – and the interview process is vital to see if he can handle being a leader that everything works around. 

2. Danny Shelton, Washington 6-2, 339
Is his lack of height a problem? A true bowling ball, he’s built for the nose, but can he be around 320 instead of being a few cheeseburgers away from 350? He’ll need to be able to somehow prove he can hold up and be in good enough shape to keep on moving even when wearing down. 

3. Malcom Brown, Texas 6-2, 320
Is he strong enough? The bench will matter since there’s no real question marks about his interior pass rushing ability. He’s always working and always moving – motor isn’t a problem – but can he be an NFL anchor who can hold up when getting plowed on? 

4. Carl Davis, Iowa 6-3, 315
Does he have the speed and quickness to become a dangerous interior pass rusher? He’s going to be a rock against the run, but the more he can show he can move outside of a phone booth, and the more quickness and burst he can show, but better the chance he has of being a top 50 pick. 

5. Eddie Goldman, Florida State 6-4, 314
Quickness, quickness, quickness. While he was a force at times for the Seminoles, he’s not a pass rusher and he’s not the type who can make enough plays behind the line to scare offensive coordinators. He’s a true nose tackle, but he has to be able to fit more schemes. 

6. Jordan Phillips, Oklahoma 6-6, 334
Can he be more than a nose tackle? How is his conditioning? The size is impressive, and he can actually move a little bit, but he’s not a pass rusher and he’s not quite consistent enough to be counted on regularly – the OU defense didn’t do enough with him as the anchor. 

7. Michael Bennett, Ohio State 6-2, 288
He has to be really, really quick. He’s not big enough, and he’s not bulky enough, so he has to make his money with the short and agility drills. He can be a dangerous interior pass rusher, but after a bit of a disappointing year after looking like a world-beater in 2013, he has to somehow prove that he’s not slopping. 

8. Xavier Cooper, Washington State 6-4, 299 
Can he look the part? He doesn’t really have the right body and the right appearance of an NFL defensive tackle, but he can move and he’s athletic. Raw strength has to be shown off – he needs a good bench press – and he has to look relatively powerful. 

9. Marcus Hardison, Arizona State 6-4, 300
Is he a big end or a smallish tackle? He needs to show strength and power, and he has to show that he’s more than a pass rusher. He’s still trying to get the finer points of the position after starting out his career on the outside, and now the scouts have to figure out exactly what he is and what he can become. 

10. Joey Mbu, Houston 6-3, 310
Can he show any explosion? He’s a rock and he can move a bit, but he has to be great in the short drills. He could turn into a major high-riser with just a little bit of mobility in the workouts. Can he play up to his size? He was a bit too inconsistent last year. 

11. Gabe Wright, Auburn 6-3, 284
Can he overcome the lack of massive bulk? He’s not a strong interior presence, and he’s coming off a shockingly mediocre season, but when he’s on, he looks like a potentially dangerous pass rushing force. He might be just a part of a puzzle and rotation, but he has to get past his issues by being more athletic than anyone else. 

12. Christian Covington, Rice 6-3, 300
The medical types will make the difference. If he’s right, he has the potential to be among the top big sleeper picks, but he has to get past a knee injury that cost him most of last year. He’s going to drop and drop far, but in three years he could be an absolute steal. First, the doctors have to say his knee isn’t going to be an ongoing concern. 

13. Grady Jarrett, Clemson 6-0, 290
Purely a nose tackle, he’s not quite big enough to be an anchor and he’s not quite athletic enough to move. For him, the bench matters. He has enough talent and skill to be a factor, but the more explosion he can show, and the more physical he can be, the better. 

14. Bobby Richardson, Indiana 6-3, 286
Where does he play? He might be an end in any scheme, but he’s mostly needed on the inside as a penetrating quick pass rusher. He’ll be a part of a rotation, but does he have anything worthy of drafting in the mid-rounds? He’s still a bit of a project, but there’s a chance he stands out in a deep field just because he can move. 

15. Derrick Lott, Tennessee-Chattanooga 6-4, 303
Is he just coming into his own or was he only great because he dropped a level? He wasn’t quite cut out for Georgia early on and ended up at UT-Chattanooga, where he was fantastic. He has the size and he has the quickness, and now he has to look like he belongs with the big boys. 

16. Tyeler Davison, Fresno State 
6-2, 309
There’s a ton to like, but he’s not going to work as a three-technique and has to be more of a run defender at the next level. He can do it all, and he could surprise and become a really, really nice value pick in the mid-rounds. A great workout could move him into the top 100. 

17. Kaleb Eulls, Mississippi State 6-4, 295 (Not Invited) 
More of a try-hard plugger than an NFL-caliber interior defender, he’s not a pass rusher and he’s not all that strong against the powerful blockers. He’ll get his chances on his pro day, and he’s going to have to be fluid. He has to look like someone who can fit into a rotation. 

18. Louis Trinca-Pasat, Iowa 6-3, 290
Is he more than a try-hard type? He was helped in a big way by being next to Carl Davis – and vice versa – and he doesn’t necessarily have NFL starter skills and tools. He’s not freakishly strong, and he’s not known for being able to move – he has to come up with a great drill or three. 

19. J.T. Surratt, South Carolina 6-2, 310
Quickness off the ball is a must. He’s a powerful interior presence at times, and he’s a nose tackle who could become an anchor, but he might only fit in a 3-4. The overall production just wasn’t there, and he’s going to have to prove to scouts that he’s not only in shape, but has some upside. 

20. Ellis McCarthy, UCLA 6-5, 325
He has to be in shape and he has to prove to the GMs and scouts that he’s going to be able to hover around 320 to 330. If he’s off, he could balloon up and turn into an unusable defender for more than just a little bit here and there. He never, ever lived up to his immense hype, and he has turned into a projection. 

21. Leterrius Walton, Central Michigan 6-5, 300
He’s going to be a tricky prospect considering what most teams would want to do with him. He needs to add at least ten more pounds, and he’s going to need time to work on his technique. He could become a dangerous all-around interior defender, but the scouts are going to have to determine if he’s worth the effort. 

22. David Parry, Stanford 6-3, 300
Purely a part of a rotation, he’s not quite big enough to do what he needs to, and he’s not quite quick enough to be anyone’s pass rusher. He’ll come across as a prime undrafted free agent, but he has to be just explosive enough to make someone want to give him a shot in the later rounds. 

23. Deon Simon, Northwestern State 6-4, 332
Really, really, really big, now he has to check out medically after suffering a knee injury. He’s not going to be all that athletic once he’s right, and he needs a lot of work, but his body mass makes him an intriguing run stopper. 

24. Leon Orr, Florida 6-5, 302
The interview process is his ticket. A superstar high school prospect, he never lived up to the hype or potential and later ended up off the team. Never healthy, and with problems with the coaching staff, he has more to prove in the meetings than he does on the field. 

25. Rakeem Nunez-Roches, Southern Mississippi 6-2, 305
Can he look like someone who can start in the NFL? He’s not tall enough and he doesn’t have the body to fit a variety of schemes. With his body type, though, he should be able to rip up the bench – he needs to crush it and be powerful to overcome the basic flaws. 

26. Angelo Blackson, Auburn 6-4, 306
Quickness – does he have any? He can take on the powerful blockers and running games, but he’s not going to get behind the line enough to make a big difference. He’s purely a nose guard who has to somehow show he can do more.

27. Darius Philon, Arkansas 6-2, 272
While he’s really fast and really athletic, he’s not big enough and doesn’t have the raw bulk. Can anyone take a chance on drafting him as an interior pass rusher? The more strength and power he can show, the better. He can’t get shoved around.