Duh.....
All run first QB's eventually fail. Most of them come into the league having the number D and a dominant running game (them being a big part of that). Their consistently gets them the ball back good/great field position partly due to high # of takeaways. The problem with the Vicks, Cams, Kluckernicks and Youngs are is they have excelled all their football lives without ever having to be a real QB. Throw Tebow into that group as well. When you are the best athlete on the field Pee Wee through college your coach is under no obligation to get you ready to be an NFL style pocket QB. That coaches job is to win, no matter what, QB fundamentals be damned. It takes thousands and thousands of repetitions, if not hundreds of thousands going through drop backs, progressions, reading the defense, etc, etc that run first QB's never get. By the time you get to the NFL it's way too late. These guys have zero pocket presence or QB instincts which is huge reason why most running QB's are always sacked the most. These guys are vicinity passers who end up killing a lot of worms throwing balls at the receivers feet. Just like Jordan couldn't hit major league pitching while trying to take up baseball at 30 years old, learning from scratch how to be an NFL pocket passing QB won't happen once you are in the league.