They said they were giving Knapp a little more action recently because his bat had come around some. But I think Alfaro is clearly the starter. 57 starts to Knapp's 29, which is almost 70% (and that includes earlier in the season when there was a two-week period where Alfaro played a little less). 3 to 2 in July and presumably will be 2 to 1 over the next two days.
60 to 70% seems like the right spread for any two catchers these days, unless you have a really top (and not older) guy. Even Realmuto has only made 70% of MIami's starts (and he's worth three more WAR than Knapp and Alfaro put together).