Some guys are obviously players, with heart, technique, work ethic, toughness etc., but they have D-2 or D-3 natural body makeup, speed and strength.
I remember Matt Baumann getting crushed by Gronkowski in the bowl game thinking, "wow, that will never work." Of course Gronkowski does that to pros, and Baumann recovered a fumble later in the game.
Our defense was light years ahead with an athlete like a Ziggy or a Van Noy making big plays that stopped drives, and even allowed a guy like Unga to do his job even better.