Booting a ground ball isn't on the coach, but allowing an infield single because you didn't get to a routine grounder quickly enough (like Urias did last week) is something that coaching and player leadership should be able to prevent. With all of this, the frequency determines if it's one bad moment which always happens in a long season or if it's a systemic issue of focus.
I don’t see how the fielding slump that Gunnar had or Urias’ declining defense are on Hyde.
I don't think any of Gunnar's errors are due to lack of focus or anything a different manager could help with. But I do think every tweener flyball that's fallen in or barely been caught is something that a manager should be able to clean up.