Zimmer was born in San Francisco, California and grew up in San Diego and attended La Jolla High School.[1] He played first base, third base, and pitched 22.1 innings during his senior year and was named team MVP after batting .410 with a .492 on-base percentage and a .701 slugging percentage with four home runs and 23 RBI. On the mound, he had a record of 3–3 with a 4.39 ERA. Zimmer was also named to the San Diego All-Academic team with a 4.20 GPA and graduated as a member of the Cum Laude Society.[2]
Zimmer played college baseballatUniversity of San Francisco and committed with the intention of playing third base for the Dons.[3] The Dons moved him to pitcher due to having an all-conference player, Stephen Yarrow, starting at third base.[4] As a freshman in 2010, Zimmer pitched 5.1 innings in five appearances. After his freshman year, he played collegiate summer baseball for the Alexandria Aces of the Cal Ripken Collegiate Baseball League.[5] In 2011, he was named first team All-West Coast Conference (WCC) after posting a 6–4 record with 89 strikeouts.[6] Following the season, he played for the Cotuit Kettleers of the Cape Cod Baseball League and went 2–5 with a 3.38 ERA in 48 innings pitched.[7][8] In 2012, Zimmer went 5–3 with a 2.85 ERA and a WCC-leading 104 strikeouts and was again named first team all-conference. Zimmer was inducted into USF's athletic hall of fame in 2020.[6]
The Royals added Zimmer to their 40-man roster after the 2015 season.[12] In 2016, he pitched only three games due to shoulder fatigue and he underwent surgery, thus ending his 2016 season.[13] Zimmer returned to action in 2017 and pitched for both Northwest Arkansas and the Omaha Storm Chasers, posting a combined 5.40 ERA with 40 strikeouts in 36.2 innings pitched between both teams.[14]
Prior to the start of the 2018 season, Zimmer was designated for assignment on March 28.[15] He was released on April 4, 2018, then re-signed to a minor league contract two days later.[citation needed] He spent the 2018 rehabilitating.[16] He elected free agency on November 3, 2018.[17]
On January 4, 2019, Zimmer re-signed with Kansas City on a major league contract.[18]
He made the Royals' 2019 Opening Day roster.[19] He made his major league debut on March 31, 2019, versus the Chicago White Sox, recording one scoreless inning, with two strikeouts.[20] He was optioned to Omaha on April 8. Zimmer bounced between the Royals and AAA Omaha for most of the year, appearing in 15 games with a 10.80 earned run average at the major league level.[21]
With the 2020 Kansas City Royals, Zimmer appeared in 16 games, compiling a 1–0 record with a 1.57 ERA and 26 strikeouts in 23 innings pitched.[22] In 2021, he went 4–1 with a 4.83 ERA and 46 strikeouts in 54 innings. Zimmer was designated for assignment on November 19[23] and was released by the Royals on November 24.[24]
