Bellaire, Texas native Josh Blum attended the Emery Weiner School in Houston, where he lettered in both baseball and football all four years he attended. Over the course of his four years with Jaguars, he posted a cumulative 0.75 ERA with 166 strikeouts in 92.0 innings. A projectable right-handed pitcher from Texas, Blum was on the radar of scouts and evaluators but went undrafted and honored his commitment to the University of Southern California instead.
Blum appeared in 11 games for the Trojans in 2022, all out of the bullpen, and posted a 12.10 ERA in 9.2 innings, allowing 9 hits, walking 14, and striking out 12.