Joe Montana
Steve Young
In Montana's case, he wasn't even "highly touted" at all. I believe he was a third-round draft pick out of Notre Dame in 1979.
In Young's case, he was "highly touted" but never got any traction early in his career -- first in the USFL, then with the lowly Tampa Bay Bucs in the NFL where he was a mediocre QB at best by any statistical measure (to the point where Tampa Bay drafted Vinny Testaverde in 1987 and traded Young away).