In the 2019 game playoff pitching is so different. The Brewers didn't even have a starting rotation, such as it is, last post-season. The Astros won the World Series with some tandems and the Dodgers weren't letting their guys go three times through the order. If Nola improves and the bullpen isn't still in tatters you might get by with him and Eflin at the top of the rotation; the question then is whether Arrieta or Pivetta is actually the best #3, and which guy only makes a start when a 4th starter is needed?
But that's a lot of questions, so would be much easier to plug in a surefire #2 or 3 in that scenario.
Also, you gotta win the division (and hopefully be one of the two best teams) to really start dreaming on your best-of-7 rotation scenarios, and in that sense the Phillies probably need help. They are still one injury or regression away from being in trouble, especially if Nola never dominates and Arrieta remains what he is.
Last year we'd already be inking in the Nola game as win, so the diminished odds on Sunday wouldn't loom as large.