Keefe isn't the guy on the ice.
The players have to be smart enough to notice when an opponent is making himself open and available I the danger areas of the ice, and react accordingly.
Of the players on the team, Mitch is the 2nd last I expect to have to bring that up to, as he is a very strong defender and normally well positioned, he trails only Matthews in these regards.
The pass was phenomenal, the chase up the ice was dumb, but not fatal. Marner didn't rotate down quickly enough and Pastrnak is not some run of the mill player.
What Marner hasn't done yet since returning from injury, is assert himself with the puck.
He hasn't been his usual silky self yet.
The timing is quite obviously still not there.
Hopefully it comes back tomorrow because Toronto can't just rely on 1 guy to be the offense and the defensive help...