On July 30, 2013, he was acquired by the Chicago White Sox in a trade that had Wendelken, Avisail García, Frankie Montas, and Cleuluis Rondon going to the White Sox, Jake Peavy and Brayan Villarreal going to the Red Sox, and José Iglesias going to the Detroit Tigers.[3] He finished the year split between the High-A Winston-Salem Dash and the Single-A Kannapolis Intimidators. In 2014, Wendelken remained in Winston-Salem for the entire year, registering a 7–10 record and 5.25 ERA in 27 games. In 2015, he split the season between the Double-A Birmingham Barons and the Triple-A Charlotte Knights, pitching to a 6–2 record and 3.20 ERA between the two clubs. The White Sox added him to their 40-man roster after the 2015 season.[4]
Oakland Athletics
On December 9, 2015, Wendelken was traded to the Oakland Athletics, along with Zachary Erwin, for infielder Brett Lawrie.[5]
In 2016, he was assigned to the Triple-A Nashville Sounds to begin the season. On May 8, 2016, he was recalled by the Athletics and made his MLB debut that night.[6] He went back and forth between Nashville and Oakland for the rest of the season before being outrighted to Triple-A on October 6, 2016.[7] Wendelken did not play in a game in 2017 after he underwent Tommy John surgery.[8]
In 2018, he began the season at Triple-A. His contract was purchased by the Athletics on July 14, 2018.[9] In 2019, Wendelken was one of four Athletics pitchers to throw 30 innings with a sub 4.00 ERA, joining Liam Hendriks, Yusmeiro Petit, and Ryan Buchter.[10] In 2020, Wendelken recorded 31 strikeouts in 25 innings and an ERA of 1.80 in 21 games. In 26 appearances for the Athletics is 2021, Wendelken posted a 4.32 ERA with 26 strikeouts. On August 10, 2021, Wendelken was designated for assignment by the Athletics.[11]
Arizona Diamondbacks
On August 11, 2021, Wendelken was claimed off of waivers by the Arizona Diamondbacks.[12] In 20 appearances down the stretch, he registered a 4.34 ERA with 13 strikeouts and 2 saves in 18.2 innings of work.
In 2022, Wendelken made 29 appearances for Arizona, but struggled to a 5.28 ERA with 21 strikeouts in 29.0 innings pitched. On July 5, 2022, the Diamondbacks designated Wendelken for assignment.[13] He cleared waivers and was sent outright to the Triple-A Reno Aces on July 11.[14] After spending the rest of the season in Reno, Wendelken elected free agency on October 13.[15]