He is Jekyll and Hyde. I think the biggest issue is that he is often playing his offside now. And that's because he's identified as better than Bitetto at it. When he was paired with Sbisa I thought it was a strong pairing, as Sbisa plays his offside pretty seamless. Kulikov, Beaulieu, Bitetto have all struggled with this. I'd be curious if the hockey people can identify a skating weakness that these 3 share. Bring Buff back in the lineup and nobody has to play their offside. Kulikov returning would also stabilize some things.
I'm not sure if it's a skating weakness per say, but when you play your off side, everything is different. you've repeated the same pivots and plays so many times one way that your muscle memory is strong, but if you don't play your off side often enough, you don't get that muscle memory. There are also other things like pulling the puck off the boards is more awkward and takes a second longer to get proper control to make a play, which is an eternity in the NHL.
I've never liked playing my off side. It just feels uncomfortable, and I'd bet for someone who has to be at peak performance to hit the baseline, that drags them down enough to not hit that delta (Bitteto). With Bealieu, it's all mental - so I'd imagine playing his off side and being uncomfortable tanks his confidence.