Stanek attended the University of Arkansas, where he played for the Arkansas Razorbacks baseball team. He was selected by the Rays in the first round of the 2013 MLB draft. He made his MLB debut in 2017. Stanek often appeared as an opener, before the Rays traded him to the Marlins in 2019. He played for the Astros from 2021 to 2023, winning the 2022 World Series.
Prior to the 2013 season, Stanek was named a pre-season All-AmericanbyBaseball America, Perfect Game, and Collegiate Baseball, and the Southeastern Conference (SEC) Pre-season Pitcher of the Year.[6][7] On March 25, 2013, Stanek was named the SEC Pitcher of the Week.[8] He finished his junior year with a 10–2 record, a 1.39 ERA, 79 strikeouts, and 41 walks in 97+1⁄3 innings. In his three years at Arkansas, he compiled a 22–8 record and a 2.55 ERA, with a batting average against of .216.[9]
Stanek began the 2015 season with Charlotte, and was later promoted to the Montgomery Biscuits of the Class AASouthern League.[15] Stanek finished 2015 with a combined 8–5 record with a 3.04 ERA between the two clubs. He returned to Montgomery in 2016, and later joined the Durham Bulls of the Class AAAInternational League; he posted a combined 4–10 record with a 4.30 ERA between Montgomery and Durham.[16] He was named to appear in the 2016 All-Star Futures Game.[17] The Rays added him to their 40-man roster after the season.[18]
The Rays promoted Stanek to the major leagues on May 13, 2017.[19] He made his major league debut the next day. He ended the 2017 season with a 5.85 ERA in 21 appearances.
In 2018, Stanek found a niche spot working as "the opener", where he found immediate success with his high 90s fastball and newly introduced splitter. In June, Stanek technically set an MLB record by throwing seven consecutive scoreless starts. However, he pitched a mere 9+2⁄3 innings across those seven starts.[20] Stanek also set a major league record with 17 straight starts allowing one run or fewer.[21] On September 5, Stanek became the first rookie in 75 years to start in back-to-back games.[22] For the majority of the season, Stanek was used as one of the Rays' "opening" starters, making 59 total appearances (29 starts). In 66+1⁄3 innings, he struck out 81 batters and recorded a 2.98 ERA.
The following season, the Rays continued using Stanek as an opener. Stanek hit the disabled list on July 20, 2019, with a hip injury.[23] He had appeared in 41 games, 27 starts in 55+2⁄3 innings.
On July 31, 2019, the Rays traded Stanek and Jesús Sánchez to the Miami Marlins in exchange for Nick Anderson and Trevor Richards.[24] On August 4, 2020, Stanek was placed on the injured list after contracting COVID-19 and returned a month later on September 4. On the year, Stanek pitched to a 7.20 ERA in nine relief appearances for the Marlins.[25] On December 2, 2020, Stanek was non-tendered by the Marlins.[26]
On January 7, 2021, Stanek signed a 1-year, $1.1 million contract with the Houston Astros.[27] For the 2021 season, he talled a 3–5 won–loss record, two saves, and a 3.42 ERA over 72 relief appearances (4th in the AL).[28]
Stanek avoided arbitration with the Astros on March 22, 2022, agreeing to a $2.1 million contract for the season.[29] He earned his first save of the season on April 27 versus the Texas Rangers, allowing one run one in the ninth and leaving runners stranded on second and third to close out a 4–3 win.[30] After entering the July 22 contest versus the Seattle Mariners with the bases loaded and tying run aboard, Stanek closed out the inning en route to a 5–2 Astros win and extended a personal scoreless inning streak to 27.[31] Stanek produced 10 straight scoreless appearances until September 25, 2022, when the Baltimore Orioles scored a run in the eighth inning.[32] In the 2022 season finale versus the Philadelphia Phillies, Stanek pitched a clean seventh to lower his ERA to 1.15, eclipsing the single-season franchise record for relievers set by Will Harrisin2019 (1.50).[33]
In 2022, Stanek also totaled 2–1 W–L with one save in 54+2⁄3 innings over 59 relief appearances.[34] The Astros advanced to the World Series and defeated the Phillies in six games to give Stanek his first career World Series title.[35]
On January 13, 2023, Stanek agreed to a one-year, $3.6 million contract with the Astros, avoiding salary arbitration.[36]
Stanek throws a 4-seam fastball which stays in the high 90s and low hundreds, as well as a slider and splitter which are in the high 80s and low 90s. In the 2024 season, he added a mid-90s sinker.