Here are a few things I didn’t like about the PH Margot in the 4th with the bases loaded:
1) Julien knows how to work a count—bases loaded favors him, even against a lefty
2) In the 4th inning, you are guaranteed to give Margot 2 abs, likely 3. (Turned out he got 3). So you are choosing to give Margot as many abs if not more than your starter, in order to get a marginal platoon advantage in one of those abs.
3) Julien is a building block for this team. If you keep pinch hitting for him in key spots (and they aren’t bringing in lefties against him in non-key spots, generally), he is rarely going to get a chance to come through in a key situation.