After playing 18 innings in a day-night doubleheader Sunday and giving Aaron Altherr only one pinch-hit at-bat, the Phillies optioned the struggling outfielder to triple-A Lehigh Valley.

Altherr is batting .171 with 80 strikeouts in 210 at-bats and has seen his playing time cut dramatically in recent weeks.

The Phillies also optioned reliever Mark Leiter Jr. to Lehigh Valley, a move that was less unexpected given the need to open a roster spot for righthander Zach Eflin, who will come off the disabled list to start Monday night's series opener against the Los Angeles Dodgers.

It's unclear how the Phillies will replace Altherr. But the 27-year-old right fielder has started only five games this month. After getting the majority of the playing time earlier this season, Altherr has been displaced by Nick Williams, who has 11 home runs in only 246 at-bats.

At one point earlier in the season, Altherr seemed to be delivering meaningful hits, even if they weren't abundant. Despite notching only 36 hits this season, he has driven in 33 runs.

But Altherr is in a 10-for-76 slump since May 31 and has only one home run in his last 111 plate appearances since a pinch-hit homer May 21 against the Atlanta Braves. In his pinch-hit appearance in the first game of Sunday's doubleheader, Altherr struck out with the bases loaded in the seventh inning.