Mullen joined the Saltdogs on July 12, 2025.  The Bakersfield, California native was selected twice in the MLB Draft.  In 2018, Mullen was selected in the 35th round by the Colorado Rockies, out of Stockdale High School (CA).  In 2021, Mullen was taken by the Tampa Bay Rays in the 11th round out of UCLA.

2025:   Pitched in one game for the Southern Maryland Blue Crabs, in the Independent Atlantic League, going 0-0, with a 108.00 ERA, in 0.1 innings, striking out one and walking two.

2024:   Did Not Play

2023:   Did Not Play

2022:   Appeared in 30 games for the Bowling Green Hot Rods (High-A, TBR), in the South Atlantic League, going 4-2, 4.44 ERA, with one start.  In 46.2 innings, Mullen recorded five saves, striking out 36 and walking 18.

2021:   Went 9-1 with a 3.39 ERA in his final season at UCLA.  In 23 games with 13 starts, Mullen recorded two saves in 77.0 innings, striking out 89 and walking 38.  Mullen appeared in four games for the Rays in the Florida Complex League, going 0-0, with a 0.00 ERA in 6.1 innings, striking out seven and walking one.

2020:   Mullen appeared in seven games for UCLA, going 0-0 with a 0.93 ERA.  In 9,2 innings, he recorded 10 strikeouts with six walks.

2019:   Pitched in four games with one start for UCLA, going 1-0, with a 0.00 ERA.  In 6.1 innings, Mullen struck out six and walked five.  During the summer, Mullen played for the Falmouth Commodores in the Cape Cod League, going 0-0, with a 7.43 ERA in nine games with one save.  In 13.1 innings, Mullen struck out 18 and walked four.

2018:   Appeared in one game for the Yakima Valley Pippens in the West Coast League, going 0-0, with a 16.20 ERA.  In one start in 1.2 innings, Mullen struck out one and walked two.