Nobody will complain, except maybe in private with the manager, about a catcher they don't want catching them.
There are varying degrees of comfort levels. Nobody is saying it is black or white or that I (or we) know more about the comfort levels than you and others do.
The Sox have a long record of giving our best starters a personal caddy/catcher. They rarely stray from that plan, unless there's an injury. There's a reason for doing this. There's a reason Sale was caught by Leon 87% of the time and Swihart 0%.
Yes, of course, Sale might quickly build up a decent comfort level with Swihart. He's had some time with Vaz (218 PAs) and still has a 1.00 better ERA with Leon. Does it tale 100 PAs, 200, 400? Does it just take practicing with the catcher in ST'ing and off days? None of us know.
We do know Sale and Price did way better with Leon. With Sale, neven better than the catchers with the White Sox (in more of a pitcher's park). With Price, Vaz has more PAs than Leon, so it can't be about "building a comfort level over time," and yet with Leon we see a 1.50 better ERA! Everybody knows Price was a better pitcher with the Rays before coming to Boston. Boston is a hitter's park, and yet, Price has a better ERA with Leon than he did with almost every catcher he pitched to in Detroit & TB.
ERA with BOS: 3.74
ERA with TBR: 3.18
ERA with DET: 2.90
ERA by catcher (180+ PAs)
2.30 Martin
2.67 Avila
2.78 McCann
2.83 Leon
2.85 Molina
3.06 Jaso
3.09 Navarro
3.61 Shoppach
3.75 Gimenez + Hernandez
3.86 Lobaton
4.19 Zaun
4.32 Vaz
(5.73 Swihart in 48 PAs)
These numbers are shocking. I'm not saying they are total predictors of what is to come, but I'm a bit surprised by some who don't seem to think there is reason for concern. I'm trying to be hopeful concerning the length of the learning curve, but I am pretty sure there will be one with Swihart and between Vaz and Sale, assuming he becomes Sale's new binky.