I know you are not, and it's entirely possible to be critical about a lot of things a manager does, yet still like him and not want him replace- like me.
Also, when I am critical, I know I don't have the whole picture, and might admit I was wrong, if I knew the reasons Cora chose option B over option A.
The scheduled days off, to me, seems to go against metrics and splits. I get why someone might think the benefits outweigh the possible losses in splits, but I disagree on this one. I think he can easily give himself a 1-2 game window before and after the "day" he wants a player to rest, and adjust once he know who is starting or sees a player is struggling or heating up near the scheduled day. Yes, other player's rest days may factor into adjustment decisions, and could have been applied without us knowing. I do remember one game, where a player asked to play on his scheduled day off, and Cora let him play.
It's the rigidity of the plan that seems to fly in the face of using data to better project success. Again, this does not mean I think I am smarter than Cora. I know I am not, but other smart managers don't do this, so I think I have a leg to stand on.
Also, in the grand scheme of everything a manager does and influences, this is pretty minor. I still really like Cora as our manager, despite some minor differences I have with his choices.