According to TLN's Nick DeSouza, the Leafs' top line of Michael Bunting, Auston Matthews and Mitch Marner, along with the top pairing of Morgan Rielly and T.J. Brodie, have been on the ice for the majority of the goals that the team has given up at 5v5. In Rielly's case, he's been on the ice for 4 of the 5 even strength goals against and was in close proximity to the shooter in each case.
Granted, it's early - and by the end of the season, none of this will matter. However, the Leafs need better from their top line and their top pairing. That's not a matter of opinion. That's a fact. If they can't figure it out here in fairly short order, head coach Sheldon Keefe may have to look at adjusting his lines temporarily until everyone starts to find their stride.