The Cincinnati Reds placed rookie right-hander Julian Aguiar on the 15-day injured list on Tuesday due to a right elbow sprain, ending his season.
The move was retroactive to Saturday. In other moves, the Reds activated right-hander Ian Gibaut from the 60-day IL and sent right-hander Alan Busenitz, who was designated for assignment on Sunday, outright to Triple-A Louisville.
Aguiar, 23, last pitched on Thursday, allowing seven runs, six hits and two walks with four strikeouts in four innings in taking the loss in a 15-3 defeat to the visiting Atlanta Braves.
He finished the season 2-1 with a 6.25 ERA, 12 walks and 19 strikeouts in 31 2/3 innings over seven starts.
The Reds had selected him in the 12th round of the 2021 MLB Draft. He made his major league debut on Aug. 19.
Gibaut, 30, has not pitched in the major leagues this season because of a right forearm strain, followed by a setback with a right calf strain. He had surgery on May 9 to relieve a compression in a nerve in his forearm.
He is a career 10-8 with four saves and a 4.10 ERA in 145 innings over 135 relief appearances. He has played parts of five seasons for the Tampa Bay Rays (2019), Texas Rangers (2019-20), Minnesota Twins (2021), Cleveland Guardians (2022) and Reds (2022-present).
Busenitz, 34, was 0-0 with a 13.50 ERA in four innings over three relief appearances this season for the Reds. He is a career 5-2 with a 4.90 ERA in 68 innings over 60 relief appearances for the Twins (2017-18) and Reds (2023-24).