At some point the team is going to have to admit that Moniak was a bust. A .746 OPS at AAA in one season is ok, but doesn't scream "need to move up" and a .424 OPS in 84 PA in the majors is not a good start (over 3 years).
The bigger problem is that he strikes out almost 50% of the time in the majors and only has one extra base hit so far. He looks extremely overmatched in almost every at bat, way too many 3 pitch strike outs. Pitchers have no fear of throwing him strikes and he can barely even put the ball in play.
Just because a guy is a #1 pick doesn't mean he should be in the majors. If he was a 20th round pick we would have already moved on from him and sadly he doesn't have any elite skills (in fact he is below average in almost every way, fielding, power, bat control) with only average speed.
I think next year is his last with an option. After that they will lose him or have to hide him on the 26 man roster.
No one is so clearly easy to be thrown into a deal while he still has minuscule value. Next year he will have none after he once again proves that there just isn't anything to get excited about with him.