I don't think it's a mistake for them.
They're not gonna win with what they have this year. They're just not. There are a few other teams that should be able to blow them out of the water.
They're trotting out the two best centers in the game on their first two lines, and then they have Staal playing in a checking role. Meanwhile, they're so thin at every other skating position, it's not even funny. They need to make a serious depth trade or they're likely going out in the second round.
Grabo could fill in for Staal on the third line, Poni gives them a scorer on the wing, Mitchell provides them with some bottom 6 depth, and Gunnar is proving himself to be a pretty good player at both ends of the ice. Three of the players are 25 or younger, so they're not losing in terms of youth, and each of those three players has potentially some good upside still.
They can give whatever reasons they want in Calgary. Maybe some of the other issues (like Phaneuf's attitude, his money, etc.) played a part, but they wanted to make a depth trade, giving up an underperforming, but elite, talent, for a few lesser talents who would collectively provide Calgary with more power.
Let's face it, Staal isn't being used anywhere near his max capabilities over there. He's providing good checking and decent scoring.
Grabo would be providing pretty much the offense Staal gives them. Mitchell would provide the checking. Gunnar provides D, and Poni gives them an option for Crosby and Malkin to pass to.
No matter how you want to look at it, they'd be adding more to their team with these four players than they are getting with Staal.
