I cannot figure out how much he second guesses himself. It's not like he was a habitual poor decision maker, I always saw him as having above average hockeyQ, knowing when and where to move the puck coming out of his own zone, and where the puck should go when handling it on the opponents blueline, too often it looks like he has a hand grenade, not knowing what to do withe it.
Physically it appears he's lost a half step, his stamina seems to be good, he can get up and down the rink all right and will still engage with the forechecker but rarely in front of the net. I can't see any appearence of a nagging injury that would be holding him back from playing the way he used to.
It's kind of like he has suddenly developed a fear of making any errors, when he does make one, its like he withdraws which leads to this hesitantcy and second guessing.
Hopefully he snaps out of it really soon, they need the real Mo, not this guy who's wearing 44 atm.
Maybe cutting a bit of his ice time, not a lot just 2 or 3 minutes at the most