I'm pretty sure Leafs' management (Nonis, Carlyle, Poulin, Loiselle, etc.) is smart enough to realize that Morgan Reilly is a much more valuable defenseman than Paul Ranger, right now. All you need to do is watch them play for a shift or two. And I imagine management watches the games with much more scrutiny than us fans do.
So, I think their decision to scratch Reilly over Ranger has more to do with Ranger's confidence, and at the same time not diminishing his asset value, than either of their actual performance on the ice. This, to me, is a long-term thinking move - perhaps Ranger can improve over the next few games where they can then legitimately shop him around in trades (perhaps more as a secondary piece, but still an asset of value nonetheless). Regardless of how he improves or doesn't, putting him in the press box for games doesn't help his trade value one bit.
If they had to play a winner-take-all game for the Stanley Cup tonight, Reilly would be in, and Ranger would be out, I have no doubts about that.
Things aren't always as they seem.