A 2011 graduate of Catholic High School (LA), Aaron was voted “Mr. Baseball” for the state of Louisiana during his senior season. He attended Louisiana State University and was honored as the 2014 National Pitcher of the Year by the College Baseball Foundation. In 2014, Aaron was a Golden Spikes Award finalist, named First-Team All-American, SEC Pitcher of the Year and First-Team All-SEC.
Aaron had 10 straight starts with two or fewer runs allowed from June 22 to August 12, 2017, the longest such streak by a Phillie since the current mound distance was established in 1893. He also allowed two or fewer earned runs and struck out seven or more batters in seven straight starts from June 22 to July 26, 2017 to become the only Phillies pitcher to do so since earned runs began to be recorded in 1912. In ’17, Aaron had the most strikeouts (184) ever by a Phillies pitcher who made fewer than 30 starts in a season. At 22 years and 329 days old on April 28, 2016 at Washington, he became the youngest Phillies starting pitcher since 1973 (Dick Ruthven, 22 years, 32 days on July 1 at St. Louis) to toss 7.0 or more scoreless innings while allowing two hits or fewer. His 0.85 WHIP in ’16 was the lowest of any Phillies starter through their first seven starts of a season since Curt Schilling (0.84) in 1998. He had a career-best 23.0-inning scoreless streak from April 22 to May 8, 2016 – the longest by a Phillies starter since Cole Hamels (24.2 IP), June 1-24, 2014, and tied for the longest in the National League in ’16 (with three others).
Aaron was the first player drafted by the Phillies to make his major-league debut the very next season since Pat Combs in 1989. He was the seventh overall selection in the 2015 amateur draft.