Or perhaps you are watching Keith too closely, looking for every single mistake he makes, all the while missing the fact that pretty much every player on the team makes the same mistakes throughout the game. Keith is just in a much more prominent role, and plays defense, so his mistakes are amplified. He is still a top ten defenseman in the NHL, along with his partner.
Now if his glaringly bad mistakes were ending up in the back of the net almost every time like a certain #4, I could see the criticism. But they're not. More often than not Keith recovers his mistakes, or his partner covers them up, and vice versa.
P.S. If anyone needed to be bashed last night, it was Frolik, and the disgrace he is every time he dons the Indian head. Oh, and the genius that decided to play him over Hayes.