What is the Big Red Flag with Randy Arozarena?

The Diamondbacks have been linked in trade talks to Tampa Bay Rays outfielder Randy Arozarena. The  Rays are known to be extremely savvy when it comes to trades. They have an uncanny ability to identify talent they can mold into their system, getting the most out of players. At the same time they often know when exactly to move a player. Any time a team is trading with the Rays, they would be wise to examine all possible red flags with extra scrutiny. 

In the case of Arozarena, there seems to be one major red flag: his ability to hit fastballs. In his first 31 games he was red hot, batting .328/.402/.613, 1.015 OPS with 9 homers and 30 RBI. That was the peak of his season however. Over his final 120 games from May 6th onwards, he hit just .234/.354/.373, .727 OPS with 14 homers and 53 RBI. What caused this five-month long slump?

A cursory look at his full season long numbers by pitch type shows that he hit four-seam fastballs and sinkers well, crushed offspeed/changeups and cutters, and struggled mightily with breaking pitches, namely sliders and curveballs. When we break out how he did against those pitch types by the before and after dates above however, a clearer picture emerges.