Cam Alldred fits the bill of a depth left-hander. He spent the year at Triple-A, aside for one inning. He tossed 66.1 innings at Indy, achieving a 4.07 ERA, 3.88 FIP, and 1.37 WHIP. Alldred only struck out 21.8% of the batters faced with an 8.8% walk rate but a solid .68 HR/9 and 47.1% ground ball rate. Alldred did have an atrocious September, and entering the final month, he owned a 2.18 ERA, 2.94 FIP, and 1.13 WHIP. Alldred is a lefty, so he provides depth in an area in which the Pirates have little depth.
Another depth lefty who made a brief major league appearance was Cam Vieaux. The lefty pitched eight major league innings, spending most of the year at Triple-A. He pitched 50 innings at Indy, working to a 3.06 ERA and 1.04 WHIP, but also had a 4.41 FIP and 1.26 HR/9 rate. He posted a relatively solid 23.7% strikeout rate and a 7.4% walk rate to go along with his overall numbers.
The Pittsburgh Pirates have a myriad of other depth relief pitchers they can call upon in the event of an emergency or multiple injuries. Travis MacGregor, Joe Jacques, Hunter Stratton, Eric Hanhold, Matt Eckelman, Noe Toribio, Brad Case, Austin Roberts, Bear Bellomy, and Cam Junker are all last-resort depth players.