Barnett is a 6'3", 270 lbs defensive end who will likely run a 4.7 or so. He bends well enough that he consistently gets his pad level lower than anyone else in football when edge rushing. I can't count the number of ball carriers Barnett has tackled from behind by being so quick in pursuit on the backside of the play. He has power moves, violent hands, and plenty of athleticism. The folks who grade college football love him. The guys who write and publish mock drafts love him. The guys who give college football players awards love him.
He is neither "undersized" nor "not an explosive athlete." He isn't on the field whipping tail on blood, guts, and desire alone. He is an elite athlete at his position and he will compare favorably to anyone not named Kongbo or Garrett when it comes to his measurables at the combine. I will say this again in plain English so you can understand. Guys as big as Barnett is are not as fast as he is unless they are complete freak athletes. There are about 5-6 freak athletes per NFL draft class.
There are several things I dislike about you as a poster. Being a fair weather fan is the big one. But number two on the list is the narcissistic personality disorder.