Fandom wouldn’t be fandom without fanatics, so overreaction just tends to come with the territory. And for the most part, when it’s well-meaning, it’s fine—even a good thing, and a healthy part of the discussion. Not that it doesn’t sometimes go wrong, or too far, and I think that’s when we get into the realm of character assassination and things like that.
I think we have an inclination to draw connections between poor performance and low degrees of effort or investment, and that’s an often inaccurate association. By and large, you can probably guarantee that the guys in the locker room are more upset about the results of games than the fans are.