Watched tape on Drew Sanders. The comp that comes to my mind is LVE. Anthony Barr is another good one.
Zone coverage is his special sauce. He's insanely long at 6'5" 240 and moves like a guy 30 lbs lighter. He flows really naturally between the QB's eyes and the receiver in his zone. When he mirrors RBs, it sometimes looks like he's barely trying. Has straight-line speed to break and close. I didn't see him in man, that wasn't Arkansas' defense, but in zone he is awesome.
With run defense, he is a gamer but doesn't really have enough power to be a difference maker. Guards move him, RBs consistently plow through him for extra yardage. As far as I can tell, he diagnoses correctly, and he's fast if you just want him to beat someone to a spot. But he's not that physical.
He wins as a pass rusher, but not really in any kind of projectible way. He just runs past tackles or goes speed to power, and banks on being the better athlete. Very Barr-ish, in that big college sack totals probably won't mean big NFL sack totals. He'll probably be a better blitzer than your average MLB, but he's no Parsons.
I would say his 1st-2nd round grade is fair. Sanders is basically a giant safety, and that's what a lot of teams want at LB these days. LB and safety are cheap positions to fill, but Sanders' athleticism will keep him from falling too far.
As far as the Cowboys go, I'd rather just pay LVE and/or Donovan Wilson. Sanders is a fit here, but I think between those two, Kearse, and Damone Clark, we are pretty well stocked on underneath defenders.