Lots of examples of QBs drafted in the Top 10 (or even top 20) to be their team's Franchise QB , who were a bust for the team that picked them, and then resurrected their career and found real success on their 2nd team?
Warren moon wasn't a top 10 draft pick. (Wasn't he a star USFL guy that came to the NFL?)
There's Young.... there's Tannehil (kind of)... and I just can't think of anyone else in like 40 years. There's a zillion Tim Couchs, Ryan Leafs, Vince Youngs and JaMarcus Russels out there....but hardly any Steve Youngs. The busts that stayed busts, probably outnumber the busts who turned it around, by 75 to 1 or more.