A big part of it had to to with a great D and a solid run game. Flacco was  far from good his rookie season, he did improve in his second season, but was still not a finished product then.  
	 
 
	You could also put Eli on that list in my opinion.  
	 
 
	Some QBs struggle some don’t, they are all different players in different situations. There is a lot we don’t see on a day to day basis with these guys.  Allen rookie season was a terrible setting for him, that’s why almost everybody who surrounded him isn’t on the team anymore. He’s showed improvement, completion percentage up, yards per game up, INTs starting to go down.  I like how he plays his best football in the fourth quarter. Bills fans are just so desperate for the the answer they have no patience and pick every little aspect of his game apart.