It was from the blindside near the boards. The possible concussion will be result of his fall to the ice and hitting his head against it, and it only happened cause he never seen the hit coming. If he saw it, he would position himself to at least mitigate the fall somehow.
I dont care if its ok by the rules. It should not be, strictly by the fact it results in serious injuries. If Mikko is done for the year now, people will now say oh bad luck and similar BS… there was no luck involved, as it was completely preventable.
If this was Toews injuring say Draisaitl, i would have said the same.