QBs who were bad at passing that became efficient

[GAVol]

Steve Young was a really poor quarterback when he entered the NFL with the Tampa Bay Buccaneers and he improved so much playing in the 49'ers system that he helped the 49'ers win a Super Bowl in 1994 and he's in the NFL Hall of Fame.

Steve Young passed for a bazillion yards at BYU. His main problem was that the Bucs were terrible.