From BP on Moniak from back at the end of the MilB season:
"5. Mickey Moniak, OF (Lakewood Blue Claws)
...“We”—the Baseball Prospectus prospect team as a group—have over 30 [live looks at Moniak].
...
Before he joined the Oakland A’s, Al Skorupa gave me a piece of pro scouting advice that has always stuck with me. Someone in the amateur scouting ranks—likely smarter than you, certainly with more information than you—decided to draft this guy. They saw something that could help a major-league team someday. It’s always good to remember that and look for it. With Moniak, naturally it isn’t hard to find. He shows excellent feel with the barrel and is a plus runner who is likely to stick in center field. If you try to get into his kitchen, he keeps his hands in well and turns on the pitch authoritatively. He has a pretty good feel for the strike zone and goes up to the plate with a plan.
...[but he has a hitch in his swing which is worse when worked away and trouble with spin and LHP]...
After all, Moniak was never supposed to have any questions about his hit tool. He was sold with a 7 hit tool, in part because he doesn’t look like Corey Ray. Is it an exaggeration to say that no 7 hitter could post a .236/.285/.342 line deep into the dog days of Summer? Maybe. But while the triple slash isn’t evidence on its own, the underlying issues he’s shown on the field reflect many of the concerns you’d have from merely looking at that triple slash.
The recent prospects we’ve thrown 7 hit tools on—who were also reasonable age and league comps for Moniak—include Raimel Tapia, Victor Robles, and Francisco Mejia. Tapia never hit lower than .305 at any minor-league stop. Robles is almost exactly a year older than Moniak and is hitting .322 in Double-A. As a 19-year-old he split his time between two A-ball levels and hit .280/.376/.423. Mejia is the ray of hope. He hit .243/.324/.345 as a 19-year-old in the Midwest League. He then rolled off a 50-game hit streak the following year. Of course, no one was calling him a future .300 hitter as a teenager. But these things can change rapidly. A year is an eternity in the life of a teenaged prospect.
...It hasn’t happened yet for Moniak. So yeah, I still don’t see $6 million in major-league tools here."