The problem is you have zero way of knowing if that has to do with the catcher or not for sure. It could be just a natural progression of the pitchers skill. But I'll play along with the notion. So if it is the case, what does the fact that the young pitchers have gotten progressively worse as the year has gone on say about AJ's ability to call a game do you think? And why should we value his control of pitchers behind the plate if that is the case?
The pitcher and the catcher are almost like a conjoined defensive unit, it's going to be hard to completely separate them no matter what kind of defensive measurement you use. It's not really something that can be 'played along with' -- the information is there, that's not up for debate, but whether or not we have the time/energy to absorb it and make a nuanced argument is another story entirely.
As to your second question ... progressively worse? In what sense? ERA? Wins?
And why would those even be your barometers?
I'm more interested in how often AJ is making Folty throw secondary stuff, or the pitch sequencing he was employing with Alex Wood versus what Wood is using in Los Angeles, things of that nature.