It's not APs fault that his team might not make the playoffs. In fact, he is the sole reason they are even in playoff contention.
MVP is a subjective award. A lot of different things are used to decide who wins this award. Offensive or defense player of the year goes mainly by stats. MVP on the other hand, well being in the playoffs is practically a requirement going by the past. If you have a great story going into the season like AP or Peyton, that helps build your case even further. Even the fact that QB's keep winning the award helps AP because I'm sure a lot of people are looking for reasons to not give it to a QB. Stats and value do matter, in fact they're the most important aspect. But when you have all the contenders lined up and everything is close enough, the first few things I mentioned are what voters will use to separate the contenders.