That's not even anywhere near the top 100 worst things Kronwall has done. I really dislike Kronwall, he is a filthy, predatory hitter, but in this case it's not even actually all that dirty just a simple interference penalty where he threw an illegal pick on the guy with a football style block. Matthews was totally unready for any kind contact and went flying 6 feet into the boards off this minor contact, hopefully he is not hurt but it's a bit of a lesson maybe to be careful when you are thinking of trying to fully stretch out to reach a loose puck when there's a lot of traffic around. Maybe that would be OK in the Swiss league but not in the NHL where anyone near you is not just going to stand aside and watch you go for that puck.