[19Yzerman19]

See I'm watching that gif over and over and Nielsen clearly hit him in the head. He lifted up his elbow when doing it, you can't see if the elbow made contact but something did. Now, he didn't hit him in the head very hard, and Kesler clearly embellishes it to draw the penalty (puts hand on face) but it's not a dive. Nielsen committed a penalty. In this case it was a head shot.

Exhibit 13,422 as to why I hate supplemental discipline being so concerned with suspending to the injury. It wouldn't have required much to go differently for that to end up causing a concussion. This is a situation where the reputation of the player who went down in Kesler is distracting from a potentially dangerous play and everyone's letting Nielsen off the hook.

EDIT: Here's a youtube clip with a couple of angles and I see nothing that would change my mind on the above - with the exception that it wasn't an elbow. It's his shoulder that makes contact.