Kronwall leaves his skates AFTER he makes contact. That's legal. I know being a Pens fan you don't quite understand the rules.
Cooke doesn't ever leave his feet and most of his questionable hits are with the actual bicep area. Watch the Savard hit. NOT an elbow. Kronwall leaves his feet everytime he hits.
Cooke blindsided Savard and intentionally aimed for his head. But I guess that's ok because he used his bicep area.