Cardinals reliever Luke Gregerson is already on the disabled list due to an impingement in his right shoulder, but MLB.com’s Joe Trezza tweets that Gregerson also had arthroscopic surgery to repair a torn right meniscus yesterday. He’ll be out for at least an additional four to six weeks following that procedure.

Signed to a two-year, $11MM contract this offseason, Gregerson has been limited to just 8 1/3 innings so far in 2018. He’s been hit hard in that time, yielding eight runs on eight hits (two homers) and three walks with eight strikeouts.

While he’s never been a flamethrower, Gregerson’s average fastball was sitting at just 87.8 mph in his limited 2018 sample — a decrease of nearly two miles per hour from last season’s average of 89.5 mph. To his credit, Gregerson’s 16.7 percent swinging-strike rate was actually the second-best mark of his career, and his 60.9 percent ground-ball rate remained considerably ahead of the league average for relievers (43.3 percent).

[Related: St. Louis Cardinals depth chart]

Gregerson is one of several Cards relievers on the shelf, joining Matt Bowman, Greg Holland, Dominic Leone and Tyler Lyons. In his absence, the Cards have leaned heavily on surprise closer Bud Norris. Young flamethrower Jordan Hicks has been the most highly used piece of a largely unproven collection of arms that have been utilized in high-leverage spots, with John Brebbia, Mike Mayers and Sam Tuivailala all being asked to pick up meaningful innings (and performing quite well in the process).