Players

RHP Zach Willeman returns to Sioux City for a third time in his career in 2026. “Willy” was part of a stellar starting rotation that finished as a team with a 4.19 ERA for the season. The Ohio native had a memorable 2025 season while he was in Siouxland after moving from the pen to the rotation following the 2024 season. He went 4-2 with 65 strikeouts in 50 innings while going 4-2 over the first month and a half of the 2025 season. The righty won his last three starts, and the team was 5-3 in his eight starts. Willeman worked at least five innings in all eight starting nods for Sioux City last season, and he would finish his time with the X’s on a high note, allowing just three earned runs over his last 28 innings with 35 strikeouts. On Friday night June 20, 2025, at Blue Cross Park in Winnipeg, Willeman held the Goldeyes hitless over 6.1 innings. He went on to work seven shutout innings and lowered his ERA to 2.34 on the year. It was the fourth straight quality start for Willeman, but his time with the X’s would soon end. Six days later on June 26, Willeman was transferred to the Cincinnati Reds organization and would spend the rest of the season at Double A Chattanooga.

Willeman would go 4-4 with a 4.34 ERA with Chattanooga in 2025, making 11 starts and one appearance out of the pen for the Lookouts. He tossed 58 innings with 33 strikeouts, yielding 56 hits and surrendering 28 earned runs. Willeman would post a 1.060 WHIP for the season. The right-hander then spent the winter season pitching at Guasave in the Mexican Winter League. Willeman was 1-3 with a 4.25 ERA in 29.2 innings in seven starts for Guasave. He added 19 strikeouts, giving up 14 earned runs in 34 hits while issuing 13 walks. Willeman signed with the Explorers again on May 1, 2026, and is expected to move into the top of the starting rotation for Sioux City.

Willeman originally joined the Explorers prior to the 2024 season after spending parts of five seasons—from 2018-2023—between the Los Angeles Dodgers, Kansas City Royals and Miami Marlins organizations. In 2024, Willeman was Sioux City’s primary bullpen set arm man. He flourished in the setup role, going 5-4 in relief with a 3.42 ERA and a 1.160 WHIP. Willeman struck out 67 batters in 50 innings while surrendering 19 earned runs on 28 hits with 30 walks. The righty made 10 straight relief appearances from July 31 to August 17, totaling 15 innings without allowing an earned run. He would pick up two relief wins in the five-game sweep of Kansas City as the X’s made their move up the standings in August. Willeman finished strong during the Explorers late-season surge, striking out 22 in his last 15.2 innings on the mound. He would finish second on the team with 14 holds in relief while the team would go 27-14 in games that Willeman pitched in during 2024.

In 2023, the righty pitched in 14 games with AA Pensacola of the Southern League with the Miami Marlins organization, putting up a 7.13 ERA with 15 strikeouts and a 1.64 WHIP. He finished his season with a 3.60 ERA over five innings across his final four appearances for Pensacola. The 2022  season was Willeman’s first professional season outside of the Dodgers organization, splitting time between Double A and Triple A for the Royals. He made the move to Kansas City’s organization as the PTBNL from the Danny Duffy trade that was made in July 2021. The righty started at AA Northwest Arkansas, pitching 22.2 innings across 16 games with a 5.16 ERA, but by the end of May, he had earned a 1.59 ERA with 14 strikeouts over 11.1 innings between May 4 and May 26. After a strong showing in May, the Royals promoted him to AAA Omaha where he posted a 3.29 ERA over 13.2 innings between June 10 and July 11. He ended the season with a 0.96 ERA over 9.1 innings during his final seven games of the season.

In 2021, Willeman returned to the mound in the minors after the 2020 hiatus. Throughout the season, he put up a 3.78 ERA across 47.2 innings out of the bullpen, also striking out 59 batters during that span. His season included a span of nearly two months where he held a 1.73 ERA over 26 innings between June 25 and Aug. 22 for the Drillers.

Prior to the shutdown, Willeman had an adjustment year at Single-A Great Lakes. Across the season, he had a 5.38 ERA with a 1.68 WHIP, starting his first five games of the season before being moved to a bullpen role.

After being selected in the 19th round of the 2017 MLB Draft by the Dodgers, the then-22-year-old first appeared for the AZL Dodgers in rookie ball, allowing one earned run over 10.2 innings in five games. He was promoted to Single-A Great Lakes, where he held a 2.16 ERA with 10 strikeouts over 8.1 innings.

Willeman was drafted out of Kent State, where he played all three of his college years. His 2017 season was his first as a true starter, beginning games in 13 of his 14 appearances. Across the season, he had a 4.91 ERA with 57 strikeouts over 66 innings. During his sophomore year of 2016, he led the Golden Flashes with 14 saves, striking out 38 in his 36.2 innings with a 2.70 ERA. He led the team in saves, posting a 2.81 ERA with 34 strikeouts over 25.2 innings, not allowing a run over his final six appearances. Willeman attended Napoleon High School in Ohio before his time in college, posting a 0.63 ERA with 121 strikeouts as a senior.