Reggie Cobb. Had he not had to redshirt year 1, and not gotten the injury bug in year 3, and not had a drug problem in year 4, he could have been the best rb in Tennessee history.
Chuck Webb also had speacial potential. Without a first year redshirt, 3rd year torn acl, and forgone 4th year, he could have also accomplished as much as Cobb could have.