Unfortunately, while Constanza has been tremendously productive, amassing more wins above replacement in three weeks of work than Heyward has all year, the new arrangement hasnt suited Jason at all. Since August 1, hes hitting .136/.269/.273, with a .143 BABIP. Hes surely getting unlucky, but he has looked uncomfortable at the plate all year, and losing his starting job hasnt helped.
...
Heyward has not been good this year. He hasnt been punished by an evil stepmother: he has seriously regressed, and its not clear why. His falling plate discipline is the biggest indicator that he seriously needs to work on his approach, but his infield fly ball rate has spiked from 8.4 percent last year to 23.7 percent this year, and if you have watched him play in any game this year, youve almost certainly seen him roll over a ball and ground it to second base. Its hard to know what to do with a young player who suddenly starts playing a lot worse. One option is the Moustakas treatment, where the player is assured by the team that he has a starting spot no matter what. Heyward hasnt received that. Hes been bumped.
No one on the Braves is pretending that this situation is permanent. If and when Constanza turns back into a pumpkin, Heyward will probably be re-inserted into the lineup. That will probably happen some time shortly before the beginning of the playoffs, which the Braves are on pace to enter as the Wild Card. In the meantime, the Braves will have to hope that Heyward is able to figure out his problems despite reduced opportunities to do so.