In fairness it Minny and Philly - those teams each were on 3 game winning streaks heading into their match up with the Leafs. Detroit is on a 3 game losing streak. Even on a back to back the Leafs have little excuse to not get a win out of this one.
Where the Leafs are in the standings every game should be winnable save for like Tampa, LA, or St Louis. However their record is not necessarily indicative of their play, as
@Bluelines mentioned, and I think the Leafs are fortunate that they were able to outscore Andersen's issues/team defense issues in October and have Andy save their butts when the offense started to dry up.
So now the Leafs have a themselves in a nice spot that a slump like this won't put them behind. And the quicker they figure it out (which they have the potential to) the better off they'll be. It's just part of the ebbs and flows of the season. The Leafs are still a good team, that should be ahead of the WC spots in the playoffs. But they're not in the contender category yet.
Now the offense drying up is partially because Matthews went down with an injury.
Matthews' carrying the load really helped mask Nylander/Marner's lack of goal scoring issues. Now those kids are still not producing currently and there isn't anyone there to help carry the load like Matthews. But it's good for their development in the long run I believe.