Munson prevented runs but struggled with control during five spring appearances in Phillies camp. While allowing just one earned run and striking out six batters in seven innings, Munson also gave up a troubling eight free passes.
In 2013 with the Diamondbacks, Munson managed a 4.12 ERA in 54 2/3 innings split between the upper levels of the minors. His ERA climbed upon reaching Triple-A, but Munson did maintain a double-digit strikeout-per-nine mark (as he has for most all of his minor league career) while dropping his walk rate to a solid 2.7 BB/9 level. Nevertheless, with a crowded bullpen shaping up in Arizona, the D'Backs did not see fit to add him to the team's 40-man roster to protect him from the draft.