The Athletic has a good article today (paywall) about some of the inner workings. Gist of it is that the past regime was too scattered and inconsistent in its approach and messages to pitchers. Current one simplifying stuff. But they did have some complimentary things to say about some of the really technical stuff happening now that was already in place. Not a total loss, and not all about Bush either.
Yeah, the McCaffrey article you mentioned (
link) helped crystalize some of how I felt about the Bloom regime. Namely, I thought they were really close. We saw things like Jeffrey Springs sucking here and then going to Tampa and thriving (until he got hurt, anyway). That, to me, suggests that they had figured out
some important things that allowed them to target the right pitchers to bring in, but hadn't figured out
enough to know how to get the most out of those pitchers once they had them in house.
And in retrospect, that's a recipe for the quick turnaround we've seen in the pitching: they already had guys here with traits that suggested success. For whatever reason, they just weren't getting as much out of them as they could. I think the best example is probably Kutter Crawford: they recognized that a pitcher in their system had come back from TJS with a top-10 IVB fastball, and that that was an important trait in the post–Spider-Tack era that meant they should stick with him even if he didn't really have a starter's build, his minor league stats did not exactly scream "ace," the early returns in MLB were awful, and his velocity was nothing special. They were right about a really important and counterintuitive thing, and they seem to have understood this by like 2021!
There turned out to be a bit more to it than that. I suspect that they would have gotten there; these are smart people we're talking about, and it's not like the Giants or the Cubs can figure something out on pitching and keep it secret for long. But it is admittedly quicker to just hire the people who have already put the pieces together in another org.