You think Dilfer was an above average quarterback? Dilfer had a career completion percentage of 55% and averaged 2,339 yards passing per season in years where he started more than 10 games. He wasn't even a game manager, he thew more picks than TDs.
In his superbowl season 34 other quarterbacks threw more yards than him. That doesn't sound above average to me. 13 QBs had more than 3000 yards (some had 4,000) while Dilfer put up 1,500. It may be easier to pass now, but it certainly wasn't as impossible as Dilfer made it seem.
Baltimore let him go immediately after their superbowl run and he spent the rest of his days as a backup QB, and not a very good one either. Dobbs could easily prove himself to be a better QB than Dilfer in the next couple years.