PITTSBURGH -- The Pirates claimed right-hander Sean Poppen off waivers from the Twins on Thursday, adding pitching depth at the outset of an offseason that’s bound to bring some roster turnover.

Poppen, 26, allowed four runs on nine hits and four walks while striking out 10 in 7 2/3 innings over six relief appearances for the Twins this year. The 6-foot-3, 205-pound righty was designated for assignment on Tuesday so Minnesota could make room for prospect Alex Kirilloff, a graduate of Plum High School in Pittsburgh.

A 19th-round pick in the 2016 MLB Draft out of Harvard University, Poppen has been a starter for most of his Minor League career. He put together a 25-21 record with a 3.38 ERA and a 1.25 WHIP while averaging a strikeout per inning over 83 appearances (72 starts) across four seasons in the Twins’ Minor League system.

Poppen has struggled during his brief stints in the Majors so far, giving up seven runs in four outings last year before posting a 4.70 ERA and 1.70 WHIP in his six appearances this year. His arsenal consists of a sinker around 94 mph, a slider that has a swing-and-miss rate around 50 percent during his time in the Majors and a changeup. He has multiple Minor League options remaining.

The Pirates cleared a spot on their 40-man roster by designating super-utility man JT Riddle for assignment. Pittsburgh signed Riddle to a one-year deal before the 2020 season, viewing him as a useful piece off the bench, but the 28-year-old hit just .149 with a .398 OPS in 69 plate appearances and made four errors in only 23 games.

Removing Riddle from their roster leaves the Pirates with 19 arbitration-eligible players this offseason. They needed to clear a spot on their full 40-man roster after outrighting catcher Andrew Susac on Wednesday because they also quietly reinstated reliever Edgar Santana from the restricted list following a season-long suspension. Pittsburgh made no announcement regarding Santana’s status, but a source confirmed his suspension -- which was announced as an 80-game ban -- is over after he sat out the entire 60-game season.

Santana put together a 3.31 ERA in 84 1/3 innings over 88 appearances from 2017-18 but hasn’t pitched in the Majors since Sept. 21 of last year due to Tommy John surgery and his suspension. The Pirates will soon need to free up more space on their 40-man roster to make room for the large group of players who ended the season on the 45-day injured list.