Before we begin, the league has already ruled that this was fine:
There will be no suspension or fine for Dennis Seidenberg on his hit on Jonathan Toews last night, per an NHL source.— Amalie Benjamin (@AmalieBenjamin) December 12, 2014
So, let's quickly take a look. Images and commentary provided by Gus Booth:
Toews did not turn his back at the last second, and he's not putting himself in a vulnerable situation, either, he's skating towards the boards with very little speed because he just missed a bouncing puck chance, and then had to change direction.
Toews was getting low in preparation to play the puck/prepare for the hit, and Seidenberg throws the forearm high into shoulder blade area. It also shows that this isn't a 50-50 puck battle -- Toews has maintained positioning on Seidenberg. Seids needs to either go for the puck, go around, or legally ride Toews into the boards to tie him up. Instead...
Seidenberg followed through high, which significantly contributes to Toews falling face-first into the boards. On first view, I thought this was a fine at best. This shot makes me wonder if a suspension is coming. I have no idea if Seids is a repeat offender.
So, uh...what do you think?