[1] In his final high school start, Allen threw a no-hitter to send University to the state championship game.

[2] Allen was selected in the 16th round of the 2017 Major League Baseball draft by the Baltimore Orioles, but opted not to sign.

[8] Allen was assigned to the High-A Lake County Captains at the beginning of the 2021 season, where he went 5–0 with a 1.58 earned run average in nine starts before being promoted to the Double-A Akron RubberDucks.

[11] Allen returned to Akron at the beginning of the 2022 season before being promoted to the Triple-A Columbus Clippers after going 5–3 with a 3.33 ERA and 104 strikeouts in 73 innings over 13 starts.

Allen struck out 8, walked 1, and gave up 1 run, picking up the win in his first career MLB start.