Hill has had many years of S&C and was already at 185 lbs in his final college year.
That, plus he had a very small number of hits on him before he turned pro, having played in community college for two years, only having played one year at Oklahoma State, and finishing off his career at West Alabama, where again, he didn't take many hits at all due to limited playing time.
Right now, Edwards is at 165 lbs, and if he can put on 20 lbs of muscle (and I think he can certainly do that very handily) I think he can also be in a similar situation by the end of college, since he's probably not going to be an every down back.