He's really undersized so you'd better have an exact role in mind for him and ask him to only do that role. Too many coaches try to take players and fit them to their scheme and end up asking them to do things they can't do and then blame the player when it doesn't work.
He is not a DE. He is a 3-tech DT who can only play in a one gap system. You have to protect him if he ever plays on running downs or against draw plays. The one gap system is great when you get into the correct gap, but if you're shooting the gap the offense wants you to shoot you give up huge creases for cutback runs. We'd need to be sure and either have a NT two gap on those plays or have a backside LB filling the cutback lane and not freelancing himself.
Has a little bit of Aaron Donald in him, but the Nikita Whitlock is much more apt. The problem is that Whitlock was much more athletic than this kid. Completely different boy types as well. Whitlock put up these numbers at his pro day:
5-10, 251
43 Bench Reps
4.82 40
1.69 10
33" Vertical Jump
9' Broad Jump
4.34 20 yard shuttle
6.91 3-cone (this is an insane time, freakish change of direction and short area burst)
Kony Ealy ran 6.83 at 6-4, 273, Mingo ran 6.84 at 6-4, 241, Watt ran 6.88 at 6-5, 290 (freak show), Vic Beasley ran 6.91 at 6-3, 246, Randy Gregory ran 6.80 at 6-5, 235. To put it into context, the average 3-cone for NFL corners at the Combine since 1999 is a 6.90. For WR's it's a 6.93.
Aaron Donald is his best size comp:
6-1, 285 at the Combine (he was technically 6'06")
35 Bench Reps
4.69 40
1.63 10
32" Vertical Jump
9'08" Broad Jump
4.39 20 Yard Shuttle
7.11 3-Cone
Two things you'll notice from these guys is exceptional change of direction skills (3-cone), and excellent vertical jump numbers (lower body explosion). Keir Thomas does not possess these traits at the moment. I'm comparing guys who were coming out of college, to a kid entering college, but you can only improve so much as an athlete in college. Sometimes you are who you are.
For me, whenever the strength numbers for our players come out I go straight to the vertical jump and squat numbers. That tells you explosive football power type movements. Our program has put up woeful numbers in these key areas and I feel that is directly reflected on the field. In my research, those two metrics are more closely related to football success than any other standard used metrics out there (I've actually seen a dissertation that indicated that lean muscle mass correlates even better than my numbers have shown, but the testing for lean muscle mass is very rigid and the numbers are not nearly as available, so the sample size is much smaller than I've produced). I put together a database for every athlete either invited to the Combine, or who was drafted into the league since 1999.
Believe it or not, height also tends to impact success on the field, so I understand why coaches are so in love with height and arm length. You have to have prototypes in mind for each position and try to live in those dimensions. You make exceptions for the rare cases, because if you make exceptions at each position, before long you have a team full of exceptions. Given the position, need, expected change in defensive philosophy, the fact he plays for a feeder program and has a star teammate we would like to take, I'd make one of those exceptions for Thomas.