Unfortunately there's in-shape and then there's game-shape.
The difference between the two can be surprising. But I don't think we're too far off hopefully.
I understood it with Kakko, who had not been skating for over 11 days because he was quarantined. He needed more than 1 session on ice before putting him back in. With Panarin (if I've understood it right) this has not been the case. He has been doing some skating, despite being away from the team. Also, he was not recovering from COVID. It's not the same thing.
But whatever, glad he's back. I hope his mere presence in the locker room is a cheer up for the boys to make a bounce-back effort against the Bruins.