What evidence do you have for such a claim, outside of the obvious “he slow” type of observations.
Arty is hard on pucks, makes smart plays, and takes short & effective shifts. There is no evidence to suggest his conditioning is suspect.
His problem is that he looses Puck battles that lead directly to the opposition immediately leaving the zone. Other players create a contest even after loosing possession but for arty atm once the battle is lost he's out of position and there's an easy exit for their D.
Gabe had the same issue last year, they'd just seem to enter a battle right as the Puck was coming out straight to where they were. He's just young and will learn, he's improving.
When we have possession artys a wizard, he has great vision so is a good fit for kopi with the Puck, I just don't think he's strong enough on a cycle the kopi likes to play.