Tony Mandarich was the first guy that came to mind. We know now it was a steroid facade but he was a beast at run blocking in college. And as terrible as he was for the Packers - exposed as a horrific pass blocker - once he got off ‘roids, pain killers & alcohol, he had a couple three productive starter years with the Colts.
He lives out in Arizona now, works as a landscape photographer, been sober 25 years. Everyone thought he was a can’t miss, ten year pro bowler. Ya just never know.