The Reds promoted Somsen to the major leagues after Jay Bruce was placed paternity list with birth of his child on April 25, 2016, but he was sent down on April 28 and did not make his MLB debut during this time on the roster, briefly becoming a phantom ballplayer.[3] Somsen was recalled on May 9 and made his MLB debut on May 14, throwing a scoreless inning against the Phillies. Somsen became the third former Jackrabbit to make his debut since 2013, joining fellow relief pitchers Caleb Thielbar and Blake Treinen.[4]
On June 22, 2016, the Los Angeles Dodgers claimed Somsen off waivers.[7] He was designated for assignment by the Dodgers on July 1,[8] cleared waivers, and was outrighted to the Triple–A Oklahoma City Dodgers on July 3.[9] He got into six games for Oklahoma City and was 0–2 with a 20.65 ERA before spending most of the season on the disabled list. The Dodgers assigned him to the Double–A Tulsa Drillers of the Texas League to start the 2017 season.[10] He split the season between Tulsa and Oklahoma City, appearing in 39 games with a 7–1 record and 2.21 ERA.[11]
In 2018, Somsen pitched in 11 games for Tulsa, allowing only one earned run in 121⁄3 innings.[11] He split the 2019 campaign between Tulsa and Oklahoma City, recording a 5.17 ERA with 13 strikeouts and 3 saves across 15+2⁄3 innings pitched. Somsen elected free agency following the season on November 4, 2019.[12]
