I'll disagree with you on this.
IMHO, the best thing that could happen for this kid is for this stupid FO to have an excuse to send him down. I think that a long-lasting, but not career-threatening injury in Spring Training, followed by a few weeks of riding busses would be the best way to get the lad's attention.
I thought it in July of '17, & I'm convinced of it now: Moncada was stupidly rushed, & his development was harmed. He can still turn it around, but his sub-.700 OPS, despite being on track for 20 HR shows how screwed up he is at the plate, & how these coaches are not helping him.