Quantrill was a four-time varsity letterman in baseball at Trinity College School in Port Hope, Ontario, and also lettered in hockey and volleyball. He was drafted by the New York Yankees in the 26th round of the 2013 Major League Baseball draft, but did not sign and chose to attend Stanford University. In his freshman season, he made 17 starts for Stanford, including their game on opening day, becoming the first freshman to start opening day for Stanford since Mike Mussina in 1988. Quantrill pitched to a 7–5 win–loss record, 2.68 earned run average, and 98 strikeouts in 110 innings pitched. In his sophomore year, Quantrill posted a 2–0 record and 1.93 ERA in 18 innings pitched before his season was cut short by an arm injury. He underwent Tommy John surgery and missed the remainder of the season and the entire 2016 season recovering. Heading into the 2016 Major League Baseball draft, Quantrill was ranked as one of the top available players by MLB. He was selected by the San Diego Padres with the eighth overall selection. The Padres signed Quantrill, and assigned him to the Arizona Padres. They promoted him to the Tri-City Dust Devils in August, and then to the Fort Wayne TinCaps later in the month. He finished the 2016 season with a combined 0–5 record and a 5.11 ERA in 12 starts between the three teams. After the season, Quantrill pitched in the San Diego Padres Futures Game, where he pitched two innings, striking out four. Quantrill spent 2017 with both the San Antonio Missions and the Lake Elsinore Storm where he posted a combined 7–10 record with a 3.80 ERA in 22 games started between both teams. He began 2018 with San Antonio. On August 6, Quantrill started with the El Paso Chihuahuas the Triple-A affiliate for the Padres. In 28 total starts between San Antonio and El Paso, he was 9–6 with a 4.80 ERA and a 1.47 WHIP. He began 2019 back with El Paso. Quantrill made his major league debut with the Padres on May 1, 2019, allowing two runs over innings pitched. He recorded his first major league win in Toronto on May 25. He was optioned to the El Paso Chihuahuas on May 26.
Personal life
Quantrill's father, Paul, played 14 seasons in Major League Baseball.
