Just trying to wrap my head around runs against differential between a very good defensive catcher (20 range, 50 glove, 80+ throwing strength and accuracy, and 90 pitch calling) versus a more league average defensive catcher who is a better offensive player. Any insights to offer? And no, before we get started, I don't want either of my catchers in RF. My current starting catcher is 15 range, 50 glove, 85 strength, 87 accuracy, 90 pitch calling, and a solid 70 against righties with 78 power. 46 eye and contact, which kinda sucks, but is this a guy that will improve my pitching staff's chances of being not awful?

I like his defense and vsR fine. Your other guy looks like a good option to platoon against lefties, too.

A long time ago I took 20 seasons of data and compared PC of my catchers. 10 pts in PC pretty much equated to .12 in ERA. This game is nothing more than plus/minus. If the better hitter can overcome his defensive inefficiency, you play him. If he can't, you play the defensive guy.

Yeah, the other catcher is basically there for duty against lefties, and he's fine as a general backup, but against righties, the defensive catcher is the better option, even with bad eye and contact.
good to know that the PC does seem to have a measurable effect on ERA. Part of this is overcompensation for the previous owner of this team, as he was playing two pretty mediocre catchers, and led the league in steals against and passed balls. I mean there was also just generally terrible defense all over the field, too, but I am above recs at every defensive spot/category except glove at 2b, which is 69. I can live with that. Hopefully this makes my mediocre pitching better, at least enough to build on the base of pretty good position players I have.