It’s 100% on Barzal himself - he needed to change the way he played. I’ve maintained that pretty consistently.
Horvat played N/S with Vancouver and came to the Isles and has pretty much done the same thing. Barzal can either skate around like the ice like he used to do or he could change his game to adapt to the team. That’s been pretty consistent. The end of last season is pretty telling that once he was out of the lineup, the change in defense play was already underway, but a way simpler game was executed, mainly because one player created a lot of unnecessary chaos on the ice that the other players didn’t know where to go or react. It reared its head again in the Carolina series.
Going to the net, not coughing up the puck, or trying to make the perfect pass are all things a player can do no matter the skill set they have and the players around them.
Barzal has played better this season, but has also had large stretches of ineffectiveness - that’s on him. See what happens the rest of the way.