The Pittsburgh Pirates made a number of changes to their roster ahead of Thursday’s game against the San Diego Padres, with the most significant change involving a struggling high-leverage relief pitcher.

The Pirates have placed right-hander Colin Holderman, who has a 16.62 ERA in his last five appearances, on the 15-day injured list with a sprained right wrist.

Holderman has allowed 11 runs (eight earned) on nine hits – including four home runs – with three walks and four strikeouts in 4 1/3 innings of work over his last five games, twice blowing leads and twice losing. Holderman has suffered losses in his last two games, allowing a three-run homer by Joc Pederson in the seventh inning of a 6-5 loss to the Arizona Diamondbacks on Sunday and three runs (one earned) on two hits and a walk in the 10th inning of a 9-8 loss to the San Diego Padres on Wednesday.

To bolster their bullpen, which was weakened by injuries and overuse after two lengthy rainouts and an extra-inning game, the Pirates acquired the contract of right-handed reliever Ben Heller from Triple-A Indianapolis.

Heller made two appearances for the Pirates this season, allowing five runs on four hits in an 11-7 loss to the Los Angeles Dodgers on June 6, and six earned runs on five hits in the 10th inning of an 11-5 loss to the Minnesota Twins three days later. Heller was designated for assignment but came through the waivers list and was sent directly to Triple-A Indianapolis, where he had a 1.33 ERA in his final 21 appearances.

To make room on the 40-man roster, the Pirates have designated for assignment outfielder Edward Olivares. Olivares, who was acquired from the Kansas City Royals in the offseason, posted a .224/.291/.333 batting average with four doubles, five home runs and 23 RBIs in 55 games for the Pirates.

The Pirates also announced that right-handed pitcher Jared Jones and outfielder Joshua Palacios will begin their rehab assignments with Indianapolis on Thursday night.