The hate is there because Flacco says he's a top QB or top-5 QB (which he probably should say I guess, gotta have confidence) and he's not even close.
Well if he should say that, seems like a lame reason to dog the guy. That said, I agree that he's no top-5 QB, and not even close at this point.
I do think he's above average. The Ravens have had lots of great defenses over the years, but they've never come close to the level of sustained success they have now. Playoff wins in 5 consecutive seasons happens once a decade on average in the NFL (I believe the Pats have also done it recently).
Point is, you're not going to achieve that with a sub-par QB.
As for his contract, he's not getting top-5 money. The Ravens are smarter than that. They'll tag him if it comes to it. Hopefully it won't so we have a little more breathing room with the cap this offseason.
With Baltimore's defense aging and players leaving or retiring they could be in real trouble. Flacco is not a "franchise QB" in my opinion and their defense and running game is what has driven the team to wins and division titles in the past.
People always assume the Raven's defense is old because of Ray and Ed. Ray and Ed are no longer the cornerstones of the defense. That torch has been passed to Ngata, Suggs, and Webb (28, 30, and 27 respectively). Unfortunately Suggs has the achilles injury and Webb tore his ACL this year. So we're seeing a down year. If they can get back to form (not a certainty IMO), then the D will be fine next year.
If anything having both of them come off the books helps our cap. Both were overpaid this season.