During Allen's freshman season at Duke, he averaged 4.4 points per game and was named to the ACC all-academic team. Allen became a major contributor in the NCAA tournament. On April 7, 2015, he played in the championship game, scoring 16 points, including 8 straight. After the game, commentators cited Allen as one of the main reasons for Duke's win. Coach Mike Krzyzewski agreed, saying, "We were kind of dead in the water. We were nine points down and Grayson just put us on his back." During the 2015–16 season, Allen was one of the best offensive players in the ACC, averaging 21 points per game and shooting 41% from three-point range. He played an average of 36.6 minutes per game and made 83.7% of his free throws. Entering his junior season, Allen was considered one of the top returning players in college basketball. He was named to the Associated Press preseason All-America team and was the ACC media's pick as preseason ACC Player of the Year. On November 29, 2016, Allen scored 24 points and 4 assist in a 78–69 win against Michigan State in the ACC-Big Ten Challenge. On December 10, 2016, Allen tallied 34 points in a 94–45 victory over UNLV. On February 9, 2017, Allen scored 25 points and 3 assist in a 86–78 win over rival North Carolina. During the 2016–2017 season, Allen averaged 14.5 points per game and shot 36.5% from three-point range. He played on average 29.6 minutes per game and was 81.1% from the free-throw line.
On June 21, 2018, Allen was selected with the 21st overall pick by the Utah Jazz in the 2018 NBA draft. On July 2, Allen inked a three-year deal worth $7,049,040 with the Jazz. He made his NBA debut on October 22, 2018 against the Memphis Grizzlies scoring 7 points in 11 minutes off the bench. On April 10, 2019, Allen scored his career-high 40 points with seven rebounds, four assists, a steal and a block in a 137–143 overtime loss to the Los Angeles Clippers.
Memphis Grizzlies (2019–present)
On July 6, 2019, the Memphis Grizzlies announced that they had acquired Allen from the Jazz.
Foul Incidents
Allen received national attention during his sophomore season at Duke following an incident during a game against Louisville Cardinals. On February 8, 2016, Allen was assessed a flagrant-one foul after he tripped Louisville forward Ray Spalding. Commentators said the move appeared to be intentional, as Allen stuck out his leg while on the ground as Spalding was hopping over him. In the second game against Louisville that season, he exchanged elbows while scuffling for a ball on the ground and later received a technical foul and ejection for yelling at a referee following his fifth foul on a charge call. On February 25, in the closing seconds of a 15-point win against Florida State, Allen tripped opposing guard Xavier Rathan-Mayes. A day later, Allen received a reprimand from the Atlantic Coast Conference for his second tripping incident in less than a month. Prior to the start of the 2016–17 season, Allen stated that he was ready to put the tripping incidents behind him. However, on December 21, he tripped Elon's Steven Santa Ana and was charged with a technical foul. The next day, Duke coach Mike Krzyzewski suspended Allen from the team indefinitely and subsequently stripped him of his team captaincy after Duke's game on December 31. Allen returned to play on January 4, 2017, after being suspended for one game. On March 9, 2018, Allen was assessed a flagrant-one foul in the ACC Tournament for tripping North Carolina's Garrison Brooks with what was called a "hip check." On July 11, 2019, Allen was ejected from an NBA Summer League between the Boston Celtics and the Memphis Grizzlies after committing back to back flagrant fouls that were called on television as "cheap shots" reacting to a "simple back screen", causing the announcers to criticize his reputation for dirty play on television and call for his removal from the game.
