I pretty much buy the CERA theory even though a lot can depend on which catcher gets to catch which starter.
In the case of Sandy Leon, I believe I see a smart catcher at work, and for exhibit A would refer to Price's last start, vs. the Guardians, when he threw 8 innings of shutout ball with 3 hits, 0 walks, and 7 K's. What I saw on my screen was Price relying heavily on his fastball and cut fastball. I saw very few changeups, sliders, or curves. Normally, usually, I would condemn such an approach, but that night it worked I think because Price had great command of the two pitches he used the most. I would further argue, that, if I'm right about what pitches Price threw that night--mostly fastballs and cut fastballs--only an experienced, confident, and insightful catcher would have done that. I also know that Sale is having a great year and has not refused any pitch Leon has called.
I have absolutely no way of telling if Sandy is great framing pitches. In fact, I don't honestly see it--that our pitchers get more calls than opposing pitchers when Sandy is our catcher. But I do honestly feel that he has a rare intelligence and feel for pitching that makes him our best defensive catcher. If he is the best, I don't really care about his hitting. Well, not much anyway.