Stephen and his wife, Jessica, were married in Montgomery, Texas before the 2024 season...His brother, Tyler Kolek, was selected second overall by the Marlins in the 2014 Draft...Graduated from Shepherd High School in Texas in 2015 and earned All-District 23-4A First Team honors as a senior...Attended Texas A&M for three years from 2016-18 and went 12-11 with a 4.03 ERA in 44 appearances (33 starts) while majoring in agribusiness.
2025
Kolek completed his second big league season in 2025, going 5-7 with a 3.51 ERA (44 ER in 112.2 IP) across 19 starts with San Diego (14) and Kansas City (5)...Began the season in Triple-A, but was recalled on May 4 and threw 5.1 shutout innings at Pittsburgh to earn his first Major League win as a starter...Made 14 starts with San Diego before being acquired by Kansas City on July 31...with the Padres, he went 4-5 with a 4.18 ERA (37 ER in 79.2 IP)…in five starts with Kansas City, he went 1-2 with a 1.91 ERA (7 ER in 33.0 IP), the eighth-lowest ERA in the Majors from Aug. 30 through season’s end (min. 5 GS)...He made his second career start on May 10 at Colorado and he threw nine shutout innings in a 21-0 rout of the Rockies, scattering five hits with seven strikeouts...he was the first visiting pitcher to throw a shutout at Coors Field since Clayton Kershaw (July 2, 2013), and the first for any team since Chad Kuhl (June 27, 2022)...He became the first pitcher to throw a nine-inning shutout that coincided with his team scoring at least 20 runs since Aug. 10, 1889, when the Cincinnati Red Stockings blanked the Baltimore Orioles in a 20-0 game behind 29-year-old rookie Jesse Duryea...There have been only seven games in baseball history that featured a nine-inning, complete game shutout with at least 20 runs scored for the winning pitcher, and the first six all came between 1883-89, per Elias...Induced 19 double plays, tied for the sixth-most in the Majors in 2025, despite having 11 of his 30 appearances come in the Minors...his 51.6% groundball rate was 12th best in the Majors (min. 100.0 IP)...He made four starts at Petco Park and he went 1-3 with a 9.45 ERA (21 ER in 20.0 IP) and .329 opponents’ average (28-for-85)…in his 15 starts away from Petco Park, he went 4-4 with a 2.23 ERA (23 ER in 92.2 IP) and .210 opponents’ average (70-for-33)...Opponents hit .049 (2-for-41) vs. his changeup, per Brooks Baseball, the lowest opponents’ batting average vs. changeups (min. 150 changeups thrown), ahead of Brandon Woodruff (.063)...Was the fourth pitcher in Royals history to record five straight quality starts to begin his tenure with the team, joining teammate Noah Cameron (2025), Jason Vargas (2014) and Steve Busby (1972), with Kolek and Vargas being the only two to pitch for a different organization prior to beginning the streak (Elias)…Kolek’s streak remains active heading into 2026...He became one of only four Royals to allow no more than seven earned runs over at least 33.0 innings in their first five appearances with the club, a feat last done by lefty Jason Vargas in 2014 (6 ER in 35.0 IP)...He made his Royals debut on Aug. 30 vs. the Tigers and made an immediate impact, logging six innings of one-run ball, limiting Detroit to just four hits (all singles) and no walks, striking out three, in an eventual 3-1 win...He became the third pitcher since 2024 to record at least six innings and allow one run or fewer in his Royals debut, following Noah Cameron (MLB debut) on April 30, 2025 at Tampa Bay and Seth Lugo on March 30, 2024 vs. Minnesota…prior to that, it hadn’t happened since southpaw Eric Skoglund did it on May 30, 2017 vs. Detroit...His 2.00 September ERA ranked fifth in the AL (min. 4 GS), trailing Tanner Bibee (1.30), Joey Cantillo (1.55), Gavin Williams (1.88) and Max Fried (1.89).
2024
At the time of his final outing of the season on July 30, his 42 appearances T-3rd most in SD’s pen with Robert Suarez, trailing only Yuki Matsui (48) and Enyel De Los Santos (42)...Allowed two ER in both of his first two ML outings…earned his first of two holds in his MLB debut on March 21 @ LAD in the Seoul Series in Seoul, South Korea…his other hold came in his 6th outing on April 7 @ SF...Following his first two big league outings, went scoreless in 14 of his next 17 outings from March 30-May 11 (1.50 ERA, 1.22 WHIP, .235 AVG)...Allowed just allowed one ER across 13 app from June 8-July 9, going 3-0 with a 0.52 ERA (1 ER, 17.1 IP), 0.98 WHIP, .215 opp. AVG and a 17-to-3 SO/BB ratio...Notched his first MLB win on June 21 vs. MIL, his first of three winning decisions over a six-outing span from June 21-July 5...Placed on the 15-day IL on July 31 with right forearm tendinitis and was transferred to the 60-day IL Sept. 1...Allowed just six barrels on the season and led all SD pitchers in barrel rate (3.8% - 96th percentile) and ground ball percentage (56.4% - 94th percentile)...Went scoreless in six of the seven outings he tossed two IP (0.64 ERA, 0.86 WHIP and .200 opp. AVG)...Walked just 12 of his 211 batters faced for a 2.3 BB/9 IP ratio that trailed only Robert Suarez (2.2 BB/9) in the SD pen...Allowed just two XBH (2 2B) to LHH (.271 AVG) while RHH batted .327 w/ 11 XBH (7 2B, 4 HR)...Once he had hitters in two-strike counts, they slashed .194/.262/.325 with 4 XBH (4 2B)...Per Statcast, relied on six pitches: sinker (40.5%), cutter (19.3%), four-seamer (13.2%), sweeper (10.4%), slider (9.7%) and changeup (6.9%).
2023
Began the season with Double-A Arkansas before being promoted to Triple-A Tacoma, where he spent the majority of the season, pitching to a 4-2 record and a 4.23 ERA (29 ER, 61.2 IP) in 44 appearances (one start) with a .224 opponent batting average. Made five scoreless appearances with Double-A Arkansas, going 2-0 and holding opposing batters to a .042 clip with a 0.39 WHIP before being promoted to TAC on April 27. Between the Double-A and Triple-A levels, he went 6-2 with a 3.76 ERA and .206 opponent average, and his 49 total appearances set a career high in a season. Allowed just three home runs in 61.2 innings pitched for Tacoma. His 44 appearances for TAC ranked third on the club, and his 49 between TAC and ARK set a new high in a single season. In the first half of the season at the Triple-A level, he went 2-2 with a 9.64 ERA (25 ER, 23.1 IP), 1.97 WHIP, and .316 opponent batting average in 15 appearances ... in 29 appearances in the season's second half, he went 2-0 with a 0.94 ERA (4 ER, 38.1 IP), 0.91 WHIP, and .154 opponents' average. Had reverse splits with TAC, holding left-handed batters to a .205 opponent clip and a .234 opponent average to righthanded batters.
2022
Spent the entire 2022 season with Double-A Arkansas, appearing in 27 games (all starts) and going 6-13 with a 4.51 ERA (72 ER, 143.2 IP), setting career highs in strikeouts (138) and innings pitched...Allowed 10 home runs, his first-career season allowing double-digit homers...Walked a career-high 66 batters in 636 batters faced but also logged a career-high 138 strikeouts.
