Of course they are. We all know this. They are probably better quarterbacks than he will ever be at any point in his career.
Manning and Brees did not win playoff games in their first 3 years in the league. That's not up for debate, it's an inarguable fact. Dalton did not win playoff games in his first 3 years either. Also not up for debate.
What I'd like an explanation for is this:
Why is it seen as perfectly fair to get rid of Dalton for failing to achieve something that guys who are better than him couldn't do either?
It's pretty much gone "Hey Andy, there's these guys that are better quarterbacks than you, right? Great, glad we're on the same page. Well, here's the situation. If you don't do what they couldn't, we're going to have to replace you."
I'd like a real, rational explanation for that. One that doesn't depend on "He sucks!" or "He can't win playoff games." to base their reasoning on.
Why is it okay to get rid of one player for not doing what better players couldn't do? I don't see the logic behind that at all. And does the same thing apply to people other than Dalton? Should we replace Gio for not breaking Eric Dickerson's rookie TD record, even though Adrian Peterson couldn't either? Should we demand that AJ be replaced for not breaking Randy Moss' rookie TD record, in spite of the fact that Calvin Johnson didn't?
It makes no sense to base the demands to replace Dalton on the fact that he hasn't won a playoff game in his first 3 years when players that are better than he's likely to ever be started their careers the same way.