Very few people like change, least of all NFL general managers and coaches. If you want to play quarterback in the NFL then you need to fit into a cookie cutter mold. Two quarterbacks from the 2012 draft class are breaking the mold and showing that when it comes to winning, there is no perfect mold.
NFL scouts want a quarterback to be 6’3″ or taller, have a strong arm with an overhand throwing motion and be comfortable making plays from the pocket.
There have always been a few outliers along the way like Fran Tarkenton and Doug Flutie, but for the most part NFL personnel want tall, pocket passers who can distribute the ball to their skill talent. The prevailing wisdom has always been that a running quarterback will get hurt in the NFL.
If the quarterback is not tall, he will not be able to see over the offensive linemen. If he does not have a rocket arm then he will not be able to make all of the throws required in the league.
Russell Wilson and Robert Griffin III have crushed these...