[Hasta la vista pelota]

Is it always better to have your best managers and coaches on the major league team?

I've inherited a previously AI-run team that has a legendary/excellent type (across all ratings, a former MLB manager) as its A-ball hitting coach. The major league staff also is excellent, except for the bench coach, who is one of those decent/OK guys.

Should I move the A-ball coach up, even to major league bench coach, or leave him where he is with the thinking that he'll give the A-ball hitters a boost?