The
Cincinnati Reds selected McLain in the first round, with the 17th overall pick, in the
2021 Major League Baseball draft. McLain signed with the Reds on July 26, 2021. McLain made his professional debut with the
Rookie-level Arizona Complex League Reds and was promoted to the
Dayton Dragons of the
High-A Central. Over 31 games between the two teams, he slashed .283/.389/.462 with three home runs, 19 RBIs, and ten stolen bases. For the 2022 season, he was promoted to the Reds' Double-A affiliate, the
Chattanooga Lookouts. In 103 games for Chattanooga, McLain slashed .232/.363/.453 with 17 home runs, 58 RBI, and 27 stolen bases. McLain was assigned to the Triple-A
Louisville Bats to begin the 2023 season. In 38 games, McLain hit .348/.474/.710 with 12 home runs, 40 RBI, and 10 stolen bases. On May 15, 2023, the Reds announced that McLain would be promoted to the major leagues for the first time the following day. In 89 games for Cincinnati, he batted .290/.357/.507 with 16 home runs, 50 RBI, and 14 stolen bases. On August 28, McLain was placed on the injured list with a right oblique strain. He began a rehab assignment with Triple–A Louisville on September 23, however he was shut down for the season on September 26 after aggravating the injury. On March 26, 2024, McLain underwent shoulder surgery to repair the labrum and some damaged cartilage, ruling him out indefinitely. ==Personal life==