It has only 1 QB because Tom Brady was unanimous. The way the voting takes place is flawed, as evidenced by Aaron Rodgers, though with only 3 starting seasons, being the all time leader in QB rating, being a SB MVP and having a SB ring, all while not having a single vote to the all-pro team in his entire career.
Would you say he was better than Brady in 2010 or Manning in 09? I thought Brees was great in 09 as well. Not saying he wasnt I just think its pretty close. Brady had such an amazing year.
Favre only had 3 All Pro years, so its never easy.