With Tebow and Leinart out of the league, I'm not aware of many (any?) lefty NFL QBs these days. Lefties have an advantage in other sports like baseball, tennis, and basketball so will often gravitate towards those areas. I've always felt that it was harder to make it as a lefty QB. Football is more about chemistry. Right tackle becomes the blind side. Handoffs, quick slants, and routine plays take more repetitions to get on same page with teammates. On the other hand, when a team goes all in on a left QB and builds a team around him, maybe it's a slight advantage since defenses are not used to the rarity. I think we'll still see a few lefty QBs in the future but will be even less than we've seen in the past.