I would agree, but there is more to being an umpire than balls and strikes. Control of the game is a hard one to categorize, and that is arguably the most important part of an umpires job, especially whoever you are going to have as the crew chief.
I think safe / out calls have become less important since they can now be fixed by review, but honestly I would still say they have some importance because sometimes a call is made and the play continues. Going back and fixing it after wards doesnt always fix the problem in those cases.
To me it would be best to have reviewable balls/strikes, but that is still a couple years away. Until then I would maybe rather see the league appoint the best crew chiefs and the evaluation put in the best other guys (balls / strikes, safe/out, other calls). The crew chief does not necessarily have to be a umpire on the field, they could just come out for "organizational" issues.