Detroit Tigers Minor Leagues Farmer was drafted by the
Detroit Tigers in the fifth round, with the 156th overall selection, of the
2013 Major League Baseball draft and signed. Farmer began the 2014 season with the Single-A
West Michigan Whitecaps, where he made 18 starts, before being promoted to the Double-A
Erie SeaWolves, where he started two games. Between Single-A and Double-A, Farmer was 11–5, with a 2.65 ERA, allowing 101 hits over 115 innings with 127 strikeouts and 28 walks. After the season, Farmer was honored as
Midwest League Pitcher of the Year.
Major leagues 2014 Farmer made his major league debut on August 13, 2014, in a game against the
Pittsburgh Pirates. In his debut, he pitched five innings, allowing four runs on six hits, while striking out four, and earning a no-decision. He was optioned to the
Triple-A Toledo Mud Hens following his debut. The Tigers called up Farmer again on August 23, 2014, to start the first game of a doubleheader against the
Minnesota Twins. In his second major league start, Farmer pitched 1 innings, allowing seven runs on five hits, while walking two, and striking out three in a 12–4 loss.
2015 In 2015, Farmer made a spot start for the Tigers on May 28, against the
Los Angeles Angels of Anaheim, when he allowed seven runs on nine hits in five innings. He was recalled by the Tigers on June 24, 2015. In 12 starts with the Mud Hens, Farmer posted a 3.56 ERA with 59 strikeouts and 22 walks in 68 innings.
2016 In 2016, Farmer made the Tigers opening day roster. On April 16, 2016, Farmer was optioned to the Toledo Mud Hens. Farmer was recalled to the Tigers on May 22, after
Drew VerHagen was optioned to Toledo that same day. On September 21, 2016, Farmer made his first major league start of the year against the
Minnesota Twins, however the game was suspended as a result of rain. In addition to the one start, Farmer made 13 relief appearances for the Tigers in 2016, posting a 4.60 ERA and 27 strikeouts in innings pitched.
2017 In 2017, Farmer began the season with the
Toledo Mud Hens. On May 26, Farmer received his second call-up of the year to Detroit. On May 27, Farmer started against the
Chicago White Sox and recorded 11 strikeouts and zero earned runs giving him his first major league win. Farmer made 11 starts for the 2017 Tigers, going 5–5 with a 6.75 ERA and 49 strikeouts in 48 innings.
2018 With the exception of one spot start, Farmer pitched the entire 2018 season out of the Tigers bullpen. He made 66 appearances, posting a 3–4 record with a 4.15 ERA, while striking out 57 batters in innings.
2019 Farmer again filled a bullpen role in 2019, with the exception of one spot start. He went 6–6 on the season with 73 strikeouts in innings, while posting career bests in ERA (3.72) and WHIP (1.271).
2020 On January 10, 2020, the Tigers avoided arbitration with Farmer, agreeing on a one-year, $1.15 million contract. In the 2020 season (23 games), Farmer had a 3.80 ERA with 14 strikeouts in innings.
2021 On January 15, 2021, the Tigers and Farmer agreed to a one-year, $1.85 million contract, avoiding arbitration. After pitching to a 12.66 ERA in 12 games to begin the season, Farmer was
designated for assignment by the Tigers on May 7. He was outrighted to Triple-A Toledo on May 11. Farmer would return to the big leagues on June 13, as his contract was selected by the Tigers from Toledo. Between send-down and call-up, Farmer made nine appearances out of the bullpen in Toledo, pitching innings, and ending with a 3.97 ERA helped greatly by a stretch of four straight scoreless outings immediately preceding his call-up. Farmer struggled to a 6.37 ERA in innings for the Tigers. On August 14, Farmer was designated for assignment by the Tigers. On August 17, he was released by the Tigers.
Texas Rangers On August 21, 2021, Farmer signed a minor league contract with the
Texas Rangers organization and was assigned to the
Round Rock Express of the
Triple-A West. In 15 appearances for Round Rock, he logged a 2-1 record and 3.60 ERA with 15 strikeouts and eight saves over 15 innings of work. Farmer elected free agency following the season on November 7.
Cincinnati Reds On March 16, 2022, Farmer signed a minor league contract with the
Cincinnati Reds. On April 4, it was announced that Farmer had made Cincinnati's
Opening Day roster. He was designated for assignment on May 6. On May 9, Farmer cleared waivers and was sent outright to the Triple-A
Louisville Bats. Farmer elected free agency and re-signed with the Reds on a minor league contract the next day. On July 9, 2022, Farmer was selected back to the active roster by Cincinnati. On August 1, Farmer earned his first career save in a 3-2 victory over the
Baltimore Orioles. He finished the year having appeared in 44 games for the Reds, posting a 2-2 record and 3.83 ERA with 54 strikeouts and two saves in 47.0 innings pitched. He became a free agent following the 2023 season. On December 28, 2023, Farmer re-signed with the Reds on a one-year, $2.25 million deal.
Atlanta Braves On February 16, 2025, Farmer signed a minor league contract with the
Atlanta Braves. In 5 appearances for the Triple-A
Gwinnett Stripers, he struggled to a 1-0 record and 7.71 ERA with 7 strikeouts across innings pitched. Farmer was released by the Braves organization on April 15.
Los Angeles Angels On May 9, 2025, Farmer signed a minor league contract with the
Los Angeles Angels. In 12 appearances for the Triple-A
Salt Lake Bees, he struggled to a 1-2 record and 9.00 ERA with 11 strikeouts and two saves across 12 innings pitched. Farmer was released by the Angels organization on June 17.
Cincinnati Reds (second stint) On July 1, 2025, Farmer signed a minor league contract with the
Cincinnati Reds. In 25 appearances for the Triple-A
Louisville Bats, he posted a 2-0 record and 1.98 ERA with 25 strikeouts and six saves across innings pitched. Farmer elected free agency following the season on November 6. ==Scouting report==