In the NFL, there has been a trend over the past decade. This trend is to have your prototypical quarterback to be at least 6 feet 4 inches tall, or a so called "pocket passer." We have seen the likes of Tom Brady, Ben Rothleisberger, and Peyton Manning. There is no doubt that these are excellent players and without a doubt, hall of fame quarterbacks.
However looking back at history, it shows that these quarterbacks are the exception and not the rule. Look no further than the last 2 quarterbacks to win the super bowl. Drew Brees is only 6 feet tall and Aaron Rogers is only 6 feet 2 inches tall.
Out of the 25 quarterbacks to win the super bowl, 64% have been 6 feet 3 inches or under. If you eliminate the Mannings, Brady, Aikman, and Rothleisberger, that number grows to 84%. It may be a safe bet to say that Michael Vick will be the next 6 footer to win it all. So unless you have an exceptional stud like one of the aforementioned players, that can put a team on his back and will his team to victory, a smart General Manager would look for one of the many excellent players who were deemed "too little."