I think he'll be good for a 3-4 team. Not big on his open field tackling or coverage skills, which are essential for a SLB in a 4-3. He should get better in those regards but he's still only a SLB. Granted there isn't much tape on him but going off the two teams he played that were good(not MAC), I thought he looked bad against Baylor and against Ohio St he pretty much only rushed(I've watched more than just those two).
There's no denying his athletic ability and pass rushing skills. I'm not arguing that but there's more than that for a SLB in a 4-3 and if you use him as a DE, he's too small, IMO. There are small DE's that are successful but they're VERY rare in today's game. SLB in a 4-3 is not important enough to be wasting the 2nd overall pick in the draft on. They could be taking a LT that will be at the very least very good for the next 7 years or so. Heck, I'm fine with taking Watkins, too, since we still don't have a #1(don't think Austin will ever be that and Bailey will probably be a good #2).
Fisher and Snead seem to fall in love with physical freaks and end up taking them WAY too early. Austin has his place but he wasn't worth #8 and #46. Brockers is a nice run stuffer but you can get run stuffing 4-3 NT's later in the draft. I hate that he was taken in the first half of the first round. Quick is big and has good speed for his size but wasn't worth anywhere near where he was taken. Khalil seems to be the next iteration of that physical freak love affair. He's a MUCH better fit for a 3-4 and has much more value in that scheme. Over the years I've developed certain beliefs and taking a SLB for a 4-3 team high in the draft is HORRIBLE value, IMO. Can anyone even name the last SLB in a 4-3 that was a game changer? Khalil may not be a reach at #2 for a 3-4 team but he is for a 4-3. At least that's how I feel about it.