But what he did Tuesday, at the major league level, in his Arizona Diamondbacks debut, facing baseball's best team, really legitimized the lower-level exploits.
Marshall used seven 95-mph fastballs -- 19 pitches in total -- to coax four Milwaukee Brewers out, never allowing a man to reach base.
He entered the game with men on first and second base in the sixth inning and got a groundout out of early MVP candidate Carlos Gomez to escape the trouble with his team unscathed.
In the following inning, he put away two via the strikeout.
And his team's three-run rally thereafter put the 24-year-old in line for the win, making him the third Diamondbacks relief pitcher to get a win in his major league debut, along with Josh Collmenter -- who happened to start Tuesday's game -- and Clay Zavada.