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.SS Landon Collins, Alabama 6-0, 222
By far the best safety prospect in a league starving at the position, now it’s about just not screwing up. He’s a first rounder, but where he goes depends on how quick he is. The 40 won’t really matter, and it’s all about the tape with him, but if he’s strong through the short drills, he might be a top 15 lock. 

2.FS Derron Smith, Fresno State 5-11, 197
If his lack of bulk is a problem for some, then he has to run really, really well. He’s a great football player who can be exactly what every and any NFL D needs, but he has to be athletic and he has to measure relatively well. As long as he’s not painfully slow, he could be an early second rounder. 

3.FS Kurtis Drummond, Michigan State 6-1, 202
Can he hit? It sounds crazy coming from Michigan State, but he’s a playmaker and he’s an athlete who can get all over the field, but strength and toughness will be a bit of a question mark. If he can be solid on the bench and can look nasty when he gets his chance, he could move up. 

4.SS Anthony Harris, Virginia 6-0, 209
Is he tough enough to be a strong safety? He’s a good pass defender and he’s a numbers guy when it comes to his tackling ability, but he has to find a true role. If he can be fast and athletic, he might be seen for a variety of roles, but he’s built to be a good starter right away. 

5.SS Jaquiski Tartt, Samford 6-1, 218
He looks every bit the part of an NFL safety with great size and excellent quickness. His draft stock could rise or fall on his 40 time, needing to blast away under a 4.6 to be a top 50 consideration. The lower level production will come into question, but as long as he looks the part in Indy, that’ll be blown off. 

6. FS Gerod Holliman, Louisville 6-2, 213
Is he that good? He came up with a special season and did everything right, but it was only one year. He could be just scratching the surface, and he has to show that in interviews. He can’t hit and won’t be a strong safety, and he might not be the right guy to build around, but in today’s NFL, he could be special. 

7.FS Cody Prewitt, Ole Miss 6-2, 217
Simply a great football player, does he have the tools to match? He has the size, and he knows how to get around the ball, and he’ll do anything needed, but can he move? Does he have the quickness? Is he physical enough? Scouts are going to want to fight for him, and he needs the workout to help the cause. 

8.FS Adrian Amos, Penn State 6-0, 209
If it’s possible to show off strength and toughness, besides the bench press, then that’s what he needs to do. He should move great, and he has decent size, but he’s not a sure-thing star unless he’s surrounded by other good defensive backs. He has to tackle. 

9. FS Eric Rowe, Utah 6-1 201
A corner who might turn into a whale of an NFL safety, he doesn’t have the speed to be on the outside, but he should show off range. Even so, he needs to come up with a big 40 to up his stock. He can’t be relatively lumbering – he has to be quick for his size. It would be nice if he could show the potential to be thrown at corner if needed. 

10.FS Tevin McDonald, Eastern Washington 5-11, 190
Character, character, character. He might not be quite big enough to be a thumper and he needs to run well, but he was great in several different ways at UCLA – and then he was dismissed from the team. As long as his issues are behind him – he failed several drug tests – then he should be a good starter as long as the workout is okay. 

11.FS Durell Eskridge, Syracuse 6-3, 207
Is he ready? He’s one of the key underclassmen who came out early who many thought should’ve come back, but he has the talent to play in the big leagues right away. With his size, he’s an intriguing prospect, but he needs the workout to show that he’s worth getting through the rocky parts to find a possible star. 

12. FS Damarious Randall, Arizona State 5-11, 190
The only thing missing is size. He’ll run well, and he’ll be athletic, and he’ll make scouts take a harder look at the tape to think that he might be a jack-of-all-trades in some NFL secondary. He’s not quite bulky enough, but if he comes up with a great workout, he could be on several draft boards around the fourth round. 

13.SS Detrick Bonner, Virginia Tech 6-1, 206
He needs to rock in the interviews when he’s asked to breakdown and diagnose. He has decent size, and he can move a bit, but there’s nothing too special about his game. He has to look like more than just another guy, and he has to come up with something in his workout that stands out. 

14.SS Clayton Geathers, UCF 6-2, 208
It’ll be impossible to change the one big concern about him in Indy – can he be consistent? He’s a great football players and he should be quick through the drills, he’s a big hitter who looks the part and has decent upside, but he’ll make two good plays and give up a big one. 

15.SS James Sample, Louisville 6-2, 191
Is he worth the patience? There’s a chance that he could turn into one of the better safeties in the draft a few years from now, and he could turn into a pet project with the right size and toughness to work in a variety of schemes. 

16.FS Chris Hackett, TCU 6-2, 195
The speed and quickness will be a question. He’s too thin and rangy to ever become a thumper of a strong safety, and he doesn’t look the part, so he has to move and he has to be fluid. He’ll do everything needed, but he has to show off the raw free safety tools. 

17. SS Kyshoen Jarrett, Virginia Tech 5-11, 200
Can he cut well and move? He’s a compact, tough hitter who likes to tackle and will make plays, but it’s possible that he’s a better college football player than a pro prospect. He’s not for everyone and every scheme, but he has to try to change all of that with a good workout. 

18.SS Jordan Richards, Stanford 5-11, 210
A consummate pro – even in college – in terms of his attitude and his character, he’s going to be the exact type of guy every coach will want running his secondary, but the athleticism has to be there. Can he run? He’s like a mini-linebacker, and he’ll get around the ball, but he has to be more of a playmaker when the ball is in the air. 

19. FS Justin Cox, Mississippi State 6-3, 190
The measurements aren’t going to make him look like an NFL safety – he’s too thin and rangy – but that’s not his problem. He can run, and he should make everyone do more research after his workout, but in today’s NFL, character concerns are a massive red flag. Cox’s off-the-field issues will make him undraftable on some boards. 

20.SS Ibraheim Campbell, Northwestern 5-11, 220
Can he cover anyone? He’s a decent-sized run stopper, but he has to come up with some decent deep speed and he has to be athletic. He was beaten too much by the better receivers, and he has to get into a better position to keep plays from happening down the field. In Indy, he has to look like more than a special teamer. 

21.FS Dean Marlowe, James Madison 6-2, 205
The size is great and the hitting ability is solid, but now he has to run. Playing at the lower level doesn’t really matter too much considering what he brings, but he’s a free safety who has to show he can run like one. He’s a risk and a flier, but he can change that with one great 40.