Castro made the All-Star team in 2013, when he was pretty much the best player on a horrible Houston Astros squad, but other than an occasional long ball he hasn't hit worth a darn since. But he is a better receiver -- specifically in terms of pitch framing -- than Kurt Suzuki, and in theory that will improve the pitching staff.
What will #MNTwins fans say more often: "Man, Castro canNOT hit!" Or, "Man, Castro sure can frame a pitch!"— John Shipley (@shipleykid) November 23, 2016
Well ... the idea is that they will say, "Man, the Twins pitching has sure gotten better."
I've no doubt that many/most Twins fans don't know that much about pitch framing numbers and other new-age evaluative stats. For that, I think, we can thank/blame a collection of broadcasters and columnists who either parrot an analytic-avoiding organization's company line or "know" nothing about catching other than that Joe Mauer's soft. Criticizing a move on the basis that fans are too ignorant to understand fails the logic test. Who's been teaching them?
Shipley's Pioneer Press colleague Mike Berardino provides some context here on the signing, Castro's pitch-framing metrics, and why that was of particular appeal to the new brain trust.
And on Twitter, he adds this disclaimer:
On the down side, some scouts believe good framers are poor blockers. Castro leads MLB w/40 passed balls 2013-16. 4th in wild pitches: 160.— Mike Berardino (@MikeBerardino) November 23, 2016
Of course, I have gone into detail on the wild pitch/passed ball problems of the Twins 2015 catchers, Suzuki and Juan Centeno. They weren't adept at framing or blocking.