Originally selected by the Tampa Bay Rays in the eighth round (243rd overall) of the 2017 Major League Baseball First-Year Player Draft...Grandson of former Cardinals infielder Johnny O'Brien (1953-59) who played in 12 games for the Redbirds in 1958...Made a pitching appearance, the first by a Cardinals position player since Pepper Martin in 1936...Johnny was also drafted by the Milwaukee Hawks of the NBA and instead chose to play baseball...His great uncle Eddie O'Brien (1953, 1955-58) played for the Pittsburgh Pirates as an infielder and also made five pitching appearances...Graduated from Shorewood (Wash.) High School, the same high school which produced two-time Cy Young Award winner, LHP Blake Snell...Played college baseball at Everett (Wash.) Community College and then at the College of Idaho, where he's the only player to appear in a Major League game as an alumni of that baseball program...Resides in Shoreline, Wash.
2023
2023 Pacific Coast League Post-Season All-Star...Spent his entire season with Tacoma (AAA) making 51 appearances with three spot starts, all in April...Posted a career-high 15 saves in 2023, ranking T-second in the Pacific Coast League...Led all Mariners Minor League pitchers with 51 appearances, 14.07 strikeouts/9 IP and 26 games finished...Did not allow a run over his final eight appearances of the season (8/31-9/22), allowing just two hits and struck out 19 batters over 8.0 innings, going 5-for-5 in save opportunities...Converted each of his last nine save opportunities...Had eight appearances of four outs or more...Made a season-high 2.0 innings pitched six times...Threw his most pitches (36) vs. Sacramento (5/31)...Posted a positive reverse split holding left-handed batters to a .167 (12-72, HR) average...Struck out 44.4% of opposing left-handed batters and 45.9% of right-handed batters.
2022
Spent the majority of the season with Triple-A Tacoma, going 1-3 with a 7.12 ERA (29 ER, 36.2 IP) with 29 walks and 43 strikeouts in 32 appearances (1 start)...made one appearance with Seattle, tossing 1.0 scoreless inning May 7 vs. Tampa Bay...began the season in the Reds organization...acquired by the Mariners from the Reds in exchange for a player to be named later or cash considerations April 17, 2022.
2021
Spent almost all of the season at Louisville, but during his three days on the Reds’ roster in the schedule’s final week made his only Major League appearance...Started the 7-1 loss on 9/28 at WSox...first strikeout victim was Eloy Jiménez, his fifth batter...in 1.1 innings allowed two hits, a solo HR to Luis Robert in the first inning and a solo HR to Yoán Moncada in the second...Became the ninth of nine Reds players to make Major League debuts in 2021 (2B Jonathan India, RHP Ryan Hendrix, RHP Vladimir Gutierrez, RHP Tony Santillan, IF Alejo Lopez, OF TJ Friedl, RHP Dauri Moreta, LHP Reiver Sanmartin)...The previous day, LHP Reiver Sanmartin made his first career appearance in a 13-1 win vs Pit...Sanmartin and O’Brien became only the fourth set of Reds starting pitchers since 1900 to make Major League debuts in consecutive games, joining RHP Rookie Davis & LHP Amir Garrett in 2017 (4/6 vs Phi, 4/7 at StL), Eddie Erautt & Bud Lively in 1947 (4/16, 4/17) and Martin Glendon & Bob Ewing in 1902 (4/18, 4/19)...Became the last of the 55 players, two shy of the 2003 club record, and the last of the 17 rookies to appear in a game for the Reds in 2021...At Louisville went 7-7, 4.55 in 22 starts and one relief appearance...was his first action above Class AA...Established professional single-season career highs in starts, innings pitched, strikeouts, batters faced and pitches thrown...Ranked among the Triple-A East pitching leaders in ERA (7th), strikeouts (4th), starts (T5th), innings pitched (8th), batting average against (3rd, .222) and WHIP (7th, 1.31)...During spring training didn’t allow a hit in 3 scoreless relief apps during “A” games (2.1ip, 1bb, 5k)...wore #84...Entered the season rated by Baseball America the 25th-best prospect in the organization.
2020
On 8/28 was acquired from the Rays for LHP Cody Reed...was assigned to the alternate training site, where he spent the rest of the regular season...Was not on the Reds' 40-player Postseason travel roster...On 11/20 was added to the 40-man roster, along with RHP Vladimir Gutierrez and RHP Jared Solomon.