Cullen has spent two seasons with Evansville. In 2019, he saw his batting average increase from his first season from .240 to .261. He also had increases in runs with 43, doubles with 12, home runs with eight, RBIs with 34, and stolen bases with 16. Before Evansville, Cullen played collegiately for Cal State Fullerton from 2015-17 after beginning his collegiate career at Saddleback College in 2014. As a senior in 2017, Cullen hit .251 and finished with eight doubles, two triples and six home runs. He appeared in 127 games for the Titans in his career and stole 11 bases. In 2018 with the Otters, Cullen batted .240 with 11 extra-base hits, 23 RBIs, scoring 38 runs, and swiped 12 bases in 2018. Defensively, Cullen had four outfield assists.