The issue is that QBs usually have to go through those mistakes to be better from them. Aaron Rodgers, Drew Brees and Peyton Manning were all turnover machines, early in their careers. San Diego didn't have the patience and drafted Philip Rivers. Indianapolis and Green Bay didn't take the ball out of their QB's hands. They let their QBs learn from those mistakes and be better from them.
The Ravens front office and overall coaching staff doesn't seem willing to let Joe go through that process, because the team is ready to win now. Joe is paying the price for that and I can completely understand his frustration.
It worked for ben roethlisberger though...and that is the model that the ravens are going after.