The Los Angeles Dodgers just can't avoid bad news about their starting pitchers this season.

Rookie River Ryan's season is over after he suffered an elbow injury during Saturday's 4–1 win over the Pittsburgh Pirates. With two outs in the fifth inning, the right-hander threw a slider and then immediately began shaking out his arm. Following an athletic trainer visiting him on the mound, Ryan was pulled from the game due to what the team called "right forearm tightness."

On Tuesday, the team announced that Ryan will need Tommy John surgery.

Before leaving the game, Ryan allowed no runs and four hits with four strikeouts in 4 2/3 innings.

His season ends with him having made four starts for the Dodgers, during which he compiled a 1.33 ERA and 18 strikeouts in 20 1/3 innings. Ryan began the season ranked by MLB.com as the team's No. 4 prospect.

Landon Knack was recalled from Triple-A Oklahoma City to fill Ryan's roster spot. In nine appearances earlier this season for Los Angeles, he struck out 42 in 44 innings with a 3.07 ERA.

Ryan told reporters Saturday that he began feeling discomfort in his right forearm in the third inning but didn't believe it was serious and used a massage gun to keep his arm loose. However, the issue became worse and couldn't be ignored in the fifth inning. Ryan said he didn't want to leave the game, but staff decided he had to be pulled.

Injuries have wiped out the Dodgers' pitching staff this season. Walker Buehler is expected to rejoin the team and pitch Wednesday, while Yoshinobu Yamamoto appears to be making progress and is expected to throw a bullpen session Tuesday.

Ryan Brasier and Connor Brogdon are set to begin minor-league rehab assignments soon. Brusdar Graterol is recovering from a hamstring strain, and Blake Treinen is dealing with left hip discomfort. Tony Gonsolin and Emmet Sheehan both had season-ending surgery, while Dustin May has a torn esophagus.