Fans are definitely justified in being disappointed or angry at how the signing turned out for last year. But the fault, really, lies with management. They signed him to the contract for the dollar value and term that they did, because of their analysis of what his play would be like with the Flames. And at least to this point, they have been very wrong about that.
The player's responsibility is to go out there and try to be the best player he can be and contribute to winning on and off the ice. There are several examples of players who don't do that, and in those situations criticism of the player is completely justified. Whether they whine to the media, demand trades and check out on the team, don't show up to meetings and set a poor example, etc., those are all things where dumping on the player is justified. If your opinion of Brouwer is that he didn't try, then it makes sense to be angry at the player, but that diverges from my own opinion for sure.
What I see is that Brouwer tried hard, but unfortunately Brouwer just isn't as good a player as his contract would suggest. I criticized the signing at the time, and given how last year went, I'm still not happy with management for signing that deal. I think it was their mistake. But I'm not angry at Brouwer, because I feel like he's, to this point, done what is asked of him, which is to play hard and do what he can on and off the ice.
And for what it's worth, I don't feel like analysis of what a player can do is the same as dumping on a player. Even saying that he should be scratched isn't dumping on a player. But "**** Brouwer" statements are just dumb, in my opinion.