For me, it's simple: the player I thought he was isn't the player he is. I thought we were getting a legit top-6 and probably 1st line power forward who drives possession, can score 30, and who would be a great running mate for one of your centers. What I got was a guy who has no hockey sense and an incredibly inaccurate shot, and makes the players he plays with worse.
Honestly can't remember ever being so disappointed in an acquisition.
Getting Tanev for Kane would be a coup.