The Philadelphia Phillies selected Biddle in the first round, with the 27th overall pick, of the 2010 Major League Baseball draft. Although he had committed to attend the University of Oregon, he agreed to a contract with the Phillies on June 10, with a signing bonus of $1.16 million. In his first season, he amassed a 3–1 win–loss record, 4.32 ERA, 41 strikeouts, and 9 walks in innings pitched for the Gulf Coast League Phillies. He also pitched in three games for the Williamsport Crosscutters that year. In 2011, Biddle pitched for the Lakewood BlueClaws where he was 7–8 with a 2.98 ERA in 25 games. That same year, Baseball America named Biddle the #2 prospect in the Phillies organization, and in 2012 Baseball America named Biddle the #1 prospect in the Phillies organization. He spent 2012 with the Clearwater Threshers where he posted a 10–6 record and 3.22 ERA in 26 starts. On April 22, 2013, with the Reading Fightin' Phils, Biddle posted 16 strikeouts in a game in Harrisburg against the Senators, breaking the previous record of 13 for his team. He spent the whole season with Reading, going 5–14 with a 3.64 ERA in 27 starts. He began 2014 with Clearwater, and after two games where he was 2–0 with a 0.90 ERA, he was promoted back to Reading and he finished the season there, compiling a 3–10 record and 5.03 ERA in 16 games started. Biddle began 2015 with Reading and on July 7, 2015, he was promoted to the Lehigh Valley IronPigs. The next day, he made his Lehigh Valley debut, giving up seven earned runs on five hits and six walks in innings pitched. In 24 starts between the two teams, he was 9–6 with a 4.95 ERA and 1.66 WHIP. Following the 2015 season, Biddle underwent Tommy John surgery.
Atlanta Braves
On February 3, 2016, the Phillies traded Biddle to the Pittsburgh Pirates for Yoervis Medina. The Pirates designated him for assignment on March 11. Biddle was claimed off waivers by the Atlanta Braves on March 19. He did not pitch at all in 2016 due to his Tommy John surgery. He returned in 2017 and pitched for the Mississippi Braves, compiling a 2–4 record and 2.90 ERA in 49.2 relief innings pitched. He began 2018 with the Gwinnett Stripers. The Braves promoted Biddle to the major leagues on April 18, 2018. He debuted in relief on April 21, throwing one inning against the New York Mets, and earning the win. Biddle recorded his first major league hit, a RBI double, against the Phillies on April 29, 2018 along with pitching two scoreless innings. On May 15, 2019, he was designated for assignment after posting an ERA of 5.40 in innings.
Seattle Mariners
Biddle was traded to the Seattle Mariners along with Arodys Vizcaino in exchange for Anthony Swarzak and cash considerations on May 20, 2019. On June 23, he was designated for assignment.
Texas Rangers
On June 28, 2019, Biddle was claimed off waivers by the Texas Rangers and formally placed on the roster on July 1, 2019. Biddle was placed in the injured list on July 16 due to elbow inflammation, which ended his season. Biddle was outrighted off the Rangers roster on October 31, 2019.
Cincinnati Reds
On January 17, 2020, Biddle signed a minor league contract with the Cincinnati Reds.
Repertoire
Biddle's main pitch is his four-seam fastball, which he can throw up to, and throws comfortably in the 90–93 mph range. He has a changeup and a slider, both of which he throws in the low 80s, a 12-to-6 curveball in the low-to-mid 70s, and a two-seam fastball in the mid-to-high 80s.
Personal
Biddle grew up in Mount Airy with his parents, David and Marion, and his brothers, Sam and Conor. He was a big fan of the Phillies and attended the 2008 World Series while in high school.
