The Padres optioned Sullivan to Triple-A El Paso on Tuesday.
Sullivan logged seven hits in 25 at-bats this spring, but he will ultimately lose out on the backup catcher job to Kyle Higashioka. Sullivan slashed .328/.401/.517 in Triple-A last season, and he could return to San Diego in 2024 if he starts the minor-league season off in similar fashion at El Paso.