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. A.J. Cann, South Carolina 6-4, 311 
There’s right tackle potential with a good drill or two showing off some lateral movement. He might be the best guard in the draft, but he could up his stock and his payday with a great workout to show off potential versatility. 

2. Tre Jackson, Florida State 6-4, 330
Does he look like he could potentially drop a little weight and be a bit more agile? At around 315 he could become the most dominant interior blocker in the draft, but he has to be able to move a bit better. 

3. Josue Matias, Florida State 6-6, 325
Is there the potential to round out his game? He’s going to have everyone buzzing after what should be a great workout, and he’ll look the part, but he’s not really a tackle and he doesn’t kill his man as a possible NFL guard. He’s a professional offensive lineman, but it’s going to take a little bit of work to figure out exactly what he is. 

4. Robert Myers, Tennessee State 6-5, 310 
While he looks like a tackle, he needs to be an NFL guard. All the tools are there and he’d be ranked higher by many if he was from Tennessee instead of Tennessee State, but he needs to destroy the bench press first. If he can do that, all of a sudden someone is going to think he could be the best interior blocker in the draft. 

5. Laken Tomlinson, Duke 6-3, 330
Does he have the ability or the potential to get on the move? He’s purely a power blocker and he’s way too clunky when he has to try to kick out and do anything when he’s outside of a phone booth. Only a guard, he has to show he’s not just for a tough run-blocking scheme. 

6. John Miller, Louisville 6-2, 312 
Does his lack of height matter? He’s not a great athlete, and he’s not the biggest blaster of a blocker, but he’s effective. He might not quite look the part, but he should blow up the bench press. That might have to be enough to overcome his lack of quickness. 

7. Jarvis Harrison, Texas A&M 6-4, 330 
Does he have the want-to and the fire to destroy his man? Is he going to show up in great shape? If the coaches can harness all of his tools, all of a sudden there might be something special there. He should test off the charts, but he needs to show the GMs that he’s going to run through a wall. 

8. Mark Glowinski, West Virginia 6-5, 312
Does he know how to play guard at a high level? More of a tackle by nature, he doesn’t really fit the mold of an NFL guard, but there are enough tools in place to be an interesting prospect. Now he has to wow everyone and make the scouts see the potential. 

9. Arie Kouandjio, Alabama 6-5, 315
Potentially a backup right tackle, and surely to be seen as just a guard, he needs to prove he can play one position and do it at a high level. While he’ll get long looks because he was a part of the Crimson Tide line, he has to look like an NFL blocker who can get on the move. He needs to be flexible and just a wee bit athletic. 

10. Adam Shead, Oklahoma 6-4, 339 
Does he have any balance and quickness? Great when he’s able to blast away, and tough as nails, there’s a lot to like, but he’s been way too banged up and he’s way too slow. He has to show the scouts that he’s going to be durable and can move his feet. 

11. Jon Feliciano, Miami 6-5, 316 
Not quick, he’s not quite for everyone. Forget about him as a tackle – even though he played there at times for the Hurricanes – and he’s not going to be a franchise guard, he can play, but he can’t be lumbering. A painfully slow time in the short-range drills could become a killer for his draft prospects. 

12. Trenton Brown, Florida 6-8, 360
What is he? At his size he’s a bit too tall for the interior, and he’s not quick enough and doesn’t have the feet to be a tackle. Was never quite healthy last year and he needs to check in at some point around 340 – and carry the weight well – to get someone to take a late round flier.