Seabold attended Newport Harbor High School in Newport Beach, California. In 2013, as a junior, he went 2–6 with a 1.97 ERA. As a senior in 2014, he pitched to a 3.80 ERA, striking out 57 batters in 46 innings. He was drafted by the Baltimore Orioles in the 19th round of the 2014 MLB draft, but did not sign and instead chose to enroll at California State University, Fullerton where he played college baseball. In 2015, as a freshman at Cal State Fullerton, Seabold appeared in 22 games, going 5–4 with a 3.26 ERA in 69 innings, striking out 76 while walking only 12. As a sophomore in 2016, Seabold became the Titan's Friday night starter a month into the year, pitching to a 7–6 record with a 2.48 ERA in 16 games, striking out 96 and walking only nine in 83 innings. He was named to the All-Big West Conference Second Team. After the season, he played in the Cape Cod Baseball League for the Yarmouth–Dennis Red Sox, helping them win the league championship. In 2017, as a junior, Seabold started 18 games, going 11–5 with a 2.96 ERA, earning a spot on the All-Big West Conference First Team.
Professional career
After his junior year, he was drafted by the Philadelphia Phillies in the third round of the 2017 Major League Baseball draft. He signed with the Phillies for $525,000 and made his professional debut with the Williamsport Crosscutters, pitching to a 0.90 ERA in ten innings. In 2018, he began the year with the Clearwater Threshers before earning a promotion to the Reading Fightin Phils in June. In 23 starts between the two clubs, he went 5–8 with a 4.28 ERA and a 1.11 WHIP as he struck out 132 batters in 130.1 innings. In 2019, he returned to Reading to begin the season, and also spent time with Clearwater. Over seven starts with Reading, he went 3-1 with a 2.25 ERA, while compiling a 1.00 ERA over two games with Clearwater. After the season, he pitched four starts in the Arizona Fall League for the Scottsdale Scorpions, going 1-0 with a 1.06 ERA as he struck out 22 batters in 17 innings. And also, on October 10, he was selected for the United States national baseball team in the 2019 WBSC Premier 12.
