Castro is a lame duck catcher. The sooner that Garver is considered the starter, and Castro the back-up and mentor, the better in my opinion. The passed balls and catcher created wild pitches that was a part of Castro's game even when healthy did not go unnoticed by me. Perhaps it escapes the advanced stats. But I saw them, and remember them. Now, Garver did not impress with a quick brain at times, but at least he is going to be here (probably) the next few years. And I don't really want an OK bat at catcher (and Castro was horrible even before his injury last year). I want a hitting catcher. And a fielding catcher. The sooner the balls and strikes are called by a non subjective method the better. Pitch framing, the art of cheating the reality of the actual location of the pitch, is a bogus skill caused by the inability of baseball to use the best tools available to make the calls more correct. Throwing the guy out at second, less passed balls, and turning wild pitches into blocks instead of creating wild pitches are the fielding skills I like.
It will be interesting to see what the arch of Astudillo is this year.
"advanced stats" absolutely would take passed balls into consideration when evaluating catcher performance, and would be the only way someone might try to capture something like "catcher created wild pitches" (which is a hilarious new stat that seems to be "I think it should have been a passed ball but the official scorer is dumb").
Castro isn't a lame duck any more than any player in their walk year is, but the fact that he's coming off a significant injury and is in that walk year means there's an opportunity for Garver to seize the job as the starter. And if either Garver or Castro goes down for any significant period of time, it opens a window for Astudillo to show he can be the next backup here, or potential to start.
Everyone wants a catcher who can hit and field.
Castro's first year with the club, he had a fine season, hitting well for the position and playing good defense while working well with the pitching staff and the catching position for the Twins was one of the more productive in baseball (8th in WAA). Last year he started slow but only played 19 games before getting hurt. That's hardly a big enough sample size to write him off as cooked.