Peterson's parents, Shannon and Doug, divorced when Peterson was a child. Peterson spent much of his childhood in stables with his father, a horse trainer who trained the likes of Seattle Slew. When Peterson was nine years old, his father died of an accidental drug overdose. Between eighth grade and his freshman year of high school, he grew ten inches.[1]
Peterson started 14 games as a freshman at Oregon in 2015, going 4–6 with a 4.39 earned run average (ERA) and 81 strikeouts.[5] As a sophomore in 2016, he went 4–5 with a 3.63 ERA and 61 strikeouts over 13 starts.[6] During the summer, he played for the United States national collegiate team.[7] Peterson became Oregon's number one starter in 2017.[8] On March 3, he set a school record with 17 strikeouts, breaking the previous record of 14 held by Tyler Anderson.[9] On April 29, he broke his record after recording 20.[10][11]
Peterson was drafted by the New York Mets with the 20th pick in the first round of the 2017 MLB draft.[12] He signed and was assigned to the Brooklyn Cyclones, where he spent the whole season, posting a 2.45 ERA in three games.[13]
MLB.com ranked Peterson as New York's second best prospect going into the 2018 season.[14] He began 2018 with the Columbia Fireflies and was promoted to the St. Lucie Mets in June.[15] In 22 total starts between the two teams, he went 7–10 with a 3.16 ERA.[16] He spent 2019 with the Binghamton Rumble Ponies,[17] going 3–6 with a 4.19 ERA over 24 starts, striking out 122 batters over 116 innings.[18]
Peterson had his contract selected to the 40-man roster on July 28, 2020. He made his major league debut on that same day, against the Boston Red SoxatFenway Park, getting the win after pitching 5+2⁄3 innings, giving up two runs on seven hits and an error with two walks and three strikeouts in 78 pitches.[19] After the start, Peterson described it as "one of the greatest days of" his life.[20]
Peterson was placed on the 10-day injured list before his start against the Miami Marlins on August 18, 2020, due to left shoulder fatigue, an issue that had arisen following his outing against the Washington Nationals on August 13, 2020.[21] He returned to the active roster two weeks later and finished the season 6–2 with a 3.44 ERA over 10 games (9 starts).
On July 2, 2021, Peterson was placed on the injured list with an oblique strain.[22] On July 24, Peterson was transferred to the 60-day injured list.[23] He finished the year having made 15 starts with a 2–6 record, 5.54 ERA, and 69 strikeouts across 66+2⁄3 innings of work.[24] In 2022, Peterson made 28 appearances (19 starts) for the Mets, registering a 7–5 record and 3.83 ERA with a 126 strikeouts across 105+2⁄3 innings pitched.[25]
Peterson made 27 appearances (21 starts) for New York in 2023, pitching to a 3–8 record and 5.03 ERA with a career–high 128 strikeouts in 111.0 innings of work.[26] Following the season on November 8, 2023, Peterson underwent surgery to repair a damaged labrum in his left hip, with an expected recovery time of six–to–seven months.[27]
On May 29, 2024, the Mets activated Peterson from the injured list for his season debut.[28]
