Minor Leagues The
Tampa Bay Rays selected McClanahan with the 31st overall selection in the
2018 Major League Baseball draft. He signed with the Rays for a $2,230,100
signing bonus. He made his professional debut with the rookie-level
Gulf Coast League Rays and was promoted to the
Princeton Rays in mid-August. In seven innings pitched between the two teams, he did not give up a run. He began 2019 with the
Bowling Green Hot Rods, was their Opening Day starter, and earned
Midwest League All-Star honors. He was promoted to the
Charlotte Stone Crabs in June after posting a 4–4 record in 11 appearances (10 starts) with a 3.40 ERA and 74 strikeouts in 53 innings pitched.
Tampa Bay Rays 2020–2021 McClanahan was selected to the 40-man roster and added to the Rays' Wild Card roster ahead of their series vs the
Toronto Blue Jays on September 29, 2020. He made his debut on October 5, against the Yankees in the
2020 American League Division Series (ALDS), becoming the first pitcher to have their debut in the postseason and fifth player overall, following
Alex Kirilloff,
Adalberto Mondesi,
Mark Kiger, and
Bug Holliday. On April 28, 2021, the Rays promoted McClanahan to the major leagues. He made his regular season debut against the
Oakland Athletics pitching four innings, allowing two runs with five strikeouts. On September 11, 2021, McClanahan was placed on the 10-day IL with back tightness. He was activated on September 19. He finished the 2021 season going 10–6 record with a 3.43 ERA and 141 strikeouts in innings.
2022 season The Rays named McClanahan as the
Opening Day starter for the 2022 season. On April 24, McClanahan took a no-hitter into the seventh inning against the
Boston Red Sox. On April 30, McClanahan had a career high 11 strikeouts in five innings against the
Minnesota Twins. On May 11, McClanahan pitched seven shut out innings and striking out 11 against the
Los Angeles Angels. He won the
American League Player of the Week Award for the week of May 8–14. McClanahan was selected to the
2022 MLB All-Star Game, after ending the first half of the season 10–3 with a 1.72 ERA and 147 strikeouts. McClanahan was named the starting pitcher for the
American League in the All-Star game. He pitched 1 innings allowing 2 runs on 4 hits. On August 31, McClanahan was placed on the 15-day IL due to a left shoulder impingement. He was activated from the IL on September 15. McClanahan finished the 2022 regular season pitching 166.1 innings, going 12–8 with 194 strikeouts and a 2.54 ERA. He finished second in
WHIP and third in
batting average against, finishing behind
Justin Verlander in the first category and Verlander and
Dylan Cease in the second.
2023 season McClanahan was the Rays' Opening Day starter for the second year in a row, where he pitched six innings of shutout ball against the
Detroit Tigers. On May 19, he pitched six no-hit innings against the
Milwaukee Brewers. McClanahan won the American League's Player of the Week Award for the week of May 15–21. On May 24, he became the third Rays pitcher to begin a season 8–0, tying
Matt Moore in 2013, and
Charlie Morton in 2019. In the month of May, McClanahan went 3–1 with a AL-leading 2.03 ERA and 40 strikeouts, earning him the
American League Pitcher of the Month Award. On July 1, McClanahan was placed on the 15-day injured list due to back tightness. On July 2, McClanahan was selected to appear in the
2023 MLB All-Star Game, the second of his career. However, McClanahan did not participate in the game due to previously being placed on the injured list for mid-back tightness. He was placed on the 60–day injured list with a left arm injury on August 12. The move ended his season, in which he made 21 starts and posted an 11–2 record, a 3.29 ERA and 121 strikeouts in 115 innings of work. McClanahan underwent
Tommy John surgery later that month.
2025 season After missing the entire 2024 season, McClanahan was set to return to the majors as the Rays' 2025 Opening Day starter, but he suffered a triceps injury while pitching against the
Boston Red Sox in spring training and began the season on the IL. He was transferred to the 60-day injured list on April 26. On August 11, the team announced he would miss the rest of the season after undergoing a procedure around the nerves. ==Pitching style==