It doesn't make any sense. P.K. Subban is an elite defenseman, one of the best players in the NHL. He's electrifying game-in and game-out, and has a personality that draws in even casual fans. Why would anyone turn on him?
Well, there are already Canadiens fans who don't like Subban. It's not a huge portion, maybe five per cent, but I've met them, I get tweets from them, and they'll have company soon. Part of that is the way Subban plays; he always has the puck so there will be more mistakes in total coming off of plays that he makes than other players, even if those mistakes are less frequent per play than anyone else on the team. Fans in general don't count puck touches like Christopher Boucher, they watch with their kids, while eating dinner, distracted, and don't care about the new stats being developed that show Subban's dominance.
But Subban's game isn't the real reason fans will turn on him, dollars are.
The player doesn't matter, the contract does
I have a fairly active twitter account, but my follower count isn't that large in context. Yet every single day, without exception, I get at least one tweet bashing Scott Gomez. No one is going to argue that the Gomez trade wasn't a disaster. No one is going to say he gave fair value for his contract, no one is going to say his last two seasons with Montreal weren't embarrassing.
However, Gomez wasn't a pariah once he started struggling, he was hated from day one. Heck, he was hated from second one.
That is, in spite of Gomez's first season with the Canadiens actually being very good. While playing against tough competition, Gomez racked up 59 points (26th in the NHL among centers), was the Canadiens' possession leader, finished third on the team in points per 60 minutes at even strength with 1.97 (30th in the NHL among centers), and topped it off with 14 points in 19 playoff games.
For the most part, any player would be seen as having a good season after that kind of production, but Gomez was booed at times during the season, a constant punching back on talk radio, and easily the most hated player on the team among fans. Why? Because he was making $7,357,143.
Gomez fell off a cliff the next year from a production standpoint, focusing even more fan rage on him, but continued to be affable in interviews with media, and liked by his teammates throughout. That doesn't really matter though.
In the salary cap era, the average fan sees the salary before the player. P.K. Subban is in his prime, and worth that contract, but he has the third-highest cap hit in the league right now thanks to the NHL's new collective bargaining agreement killing long term "career" deals. For many, Subban will have to be perfect in order to be "worth it," regardless of the reality of the situation.
With money comes expectations, and because Subban's cap hit is double that of Max Pacioretty, and $2.5M more than Carey Price's the expectations are going to be obscene.
It's going to happen, and Subban will deal with it without breaking a sweat, probably win a couple additional Norris Trophies along the way, and maybe a Stanley Cup or two, but be prepared for it. Fans are fickle, and P.K. is an easy target.