This is a very interesting article I found about this company called Achievement Metrics. They analyze the speech patterns of college QB's as a way of assessing their potential to succeed at the NFL level.
Basically, the more a player believes in himself and compliments those around him, the more likely (theoretically) he is to be a starter. Blaine Gabbert grades out somewhat favorably. Two players who do not grade out favorably are Cam Newton and... Tim Tebow.