He got his first concussion because he was a young player, probably feeling a little overconfident after his rookie year, and he was skating around with his head down, attempting to dipsy-do around players that will play the body willingly. His second concussion happened for essentially the same reason. To his credit, he's gotten much better at both avoiding and taking hits.
If you mean his current injury, it's a wrist injury. Has nothing to do with his previous injury history. Looked like be tweaked it taking a shot, with a possible link to a slash he took up high earlier in the season
He spends too much time admiring his Calder Trophy instead of working on his conditioning?
Probably just like you spend too much time admiring how clever you think you are. Skinner trains harder than 99% percent of the NHL. That and his hockey IQ are the only reason why he's a premier offensive player in the league.