Didn't the Packers draft Bruce Clark in the first round - and he went off and played in the CFL. He was picked in the top 5 overall and never played a down for the Packers. I would call that a bigger bust than Reynolds, Mandarich, and Harrell.
That is one way to look at it. I think that was a dumb pick. The Packers dumbest pick, was QB Rich Campbell. I will always remember Zeke Bratkowski's comments. He said "I was so excited when we picked him. When he arrived and threw his first pass, my hear sunk. I knew, with that throwing motion, he would never be successful in the NFL."
Now, when the OC thinks you are going to fail, what chance do you have? Also, why didn't he pay attention to his throwing motion when they scouted him? I mean, what the hell? I'm sure Campbell didn't change his throwing style as soon as he joined the Packers.
As far as Mandrich goes, you have to have been there to understand. There have been 3 uber hyped players in the last 40 years. Elway, Bo Jackson and Mandrich. He was supposed to change the NFL. He is the only college player to make the 'All Madden Team'. They invented the term 'Pancake Block' because of him (at least 1 version of the story). ESPN would run highlights of him after every game - isolating an OL on every play! They showed every devestating block. He would on occassion take out 3 or 4 defenders on a single play. When he was drafted the announcer said he was a shoe-in for Canton. He stopped with the steroids, started drinking heavily, and he wasn't good enough to even start for a very pathetic Packer team. Although he played, he was dominated by even a below average DL.
To me, bust is defined as the degree by which you fail to live up to expectations. The distance by which Mandrich missed his expectations is greater than any player in history. In my opinion, that makes him the biggest bust in NFL history.