I'm not just focusing on run differential (and f*** Michael Kay). But there's a reason it is what it is.
The other issue with season long statistics is they don't necessarily tell the story of where a team is now. The Yankees did a good job of fixing some of their holes at the deadline. They have a closer they trust, they improved their left side defense and roster flexibility and got one of the better base stealers in the league in the event that they need to steal a run late.
They still have the Judge/Stanton defensive issue to deal with, but then again we have Springer, Santander and Bo situation potentially to deal with defensively.
We got a starter that we needed, we got a couple of decent bullpen arms, but we still don't have a closer that we trust nor did we get more power, which we don't have enough of, mostly because of Vlady's disappointing power. And our starting rotation situation is super thin. Theirs isn't.
They aren't perfect, but neither are we. But I still think they're better, and they've been there before.
Doesn't mean we can't win a series against them, doesn't mean anyone can't win a series against them. But that's just the way playoff baseball is.