The dynamic is a bit black-box, but the responsibility falls on both of them to a degree. More though, I think on Bloom, unless Cora is not talking to him (which I think very very unlikely.) And I use "Cora" in his role as the head of the coaching staff entire.It has to be this way. These are both smart & successful in basebal. I can't imagine Cora saying "I think we can do this better with 13 pitchers and an extra bench player," and Bloom saying "no." They ultimately might not agree on the personel move, because Bloom has multiple considerations. Cora might say, "Chaim, Workman's got nothing left, you can leave him on the tarmac," and Bloom might say, "I agree about his pitching, but I need to keep him in the org for a little while because [making this up, obviously] he might be useful as a throw-in to a couple of things I'm working on."
I can see Cora having a mandate to play or develop a player as a regular - say Dalbec. And his numbers are there for everyone to see. But it's hard to fathom the shape of that. Is the staff insisting they're seeing progress? Is Bloom? Or is Bloom saying there's no way they can upgrade? (And what of the Santana/CA first base experiments, or Franchy in AAA?)
Either way, 1B has been an ongoing problem this year that hasn't been fixed.