Yeah, I thought the same thing re: Skjei's call.
I was away from the TV for the McGinn hit, so can't comment.
Necas, to me, stopped away from the board and turned his back almost as if he was bracing for a hit and thus got hit like he did. I didn't think it should be called when I first saw it live and still feel that way. The boarding rule, as written, includes:
"However, in determining whether such contact could have been avoided, the circumstances of the check, including whether the opponent put himself in a vulnerable position immediately prior to or simultaneously with the check or whether the check was unavoidable can be considered."
Necas clearly did put himself in that vulnerable position so I can see why it wasn't called. It's a judgement whether or not the hitter could have still avoided it, so I can see why Tripp would say what he did, but that's a lot easier to say watching something in slow motion than in real time. Thankfully Necas wasn't hurt.
He'll want to learn from Aho who lowers his center of gravity and pushes his shoulder back to the attacker to ward off hits like that.