Off the top of my head, I can think of 2 guys I saw live, I would not have offered. I saw the Warren Harding team that had Prescot Burgess and Mario Manningham I believe 3 times. Manningham appeared to be a truly elite athlete, very sorry we didn't get him.
Burgess, other than looking great in a football uniform showed me nothing. Played SS on D and TE on O. Showed no nose for the ball on D, and didn't even try and block at TE. Most overrated player I ever watched.
Another player who didn't impress me was Antonio Pittman. The game I saw was against a very average Massilion team. Pittman went fo a little less than 130 yards on 30 carries. Didn't show "vision", didn't break any tackles, and was caught for behind by kids who didn't get any D-1 offers.
Pittmann went in the 4th round of the draft. My opinion was, if Pitman played for Nwestern, he goes on drafted. If Sutton, played on the OSU offense, he would have been a day 1 pick.