Bae was optioned to Triple-A Indianapolis on Tuesday, Kevin Gorman of TribLive.comreports.
Bae started three of Pittsburgh's previous four games, but he's mired in a 3-for-23 slump and will return to the minors. Oneil Cruz is making the transition to center field, while Isiah Kiner-Falefa is poised to serve as the club's primary shortstop for the rest of the season.