The Pittsburgh Pirates have placed struggling Colin Holderman on the 15-day injured list with a sprained right wrist. To fill his spot on the roster, the Pirates have acquired Ben Heller from Triple-A Indianapolis.

In 44 appearances out of the bullpen this season, Holderman is 3-5 with a 3.21 ERA and 47 saves in 42 innings.

After a good start to the season, Holderman has struggled recently. He has been scored against in each of his last five appearances and has allowed nine earned runs on nine hits in 4.1 innings. He suffered a loss to the Padres on Wednesday after allowing three runs in the 10th inning.

Since June 23, Holderman has a 7.63 ERA in 16 appearances after posting a remarkable 0.68 ERA in 28 appearances to that point.

Heller played briefly with the Pirates in early June and was roughed up in two appearances, allowing 12 runs (11 earned) and nine hits in two innings pitched.

In 30 appearances with Triple-A Indianapolis, Heller went 2-3 with a 3.55 ERA and four saves. He struck out 63 batters, walked 13 and allowed 22 hits in 37 innings pitched.

To bring Heller back to the 40-man roster, the Pirates brought in outfielder Edward Olivares. Olivares started the season 55 times for the Pirates, hitting a modest .224/.291/.333 average with four doubles, five home runs and 23 RBIs in 55 games.

In addition, right-handed pitcher Jared Jones (right back strain) and outfielder Joshua Palacios (left hamstring strain) will begin rehab activities with Indianapolis on Thursday. Jones has been out since starting against the Cardinals on July 3, going five innings. Palacios was placed on the 10-day injured list on July 31.