[Related: Updated Phillies Depth Chart]
Stumpf was a Rule 5 selection over the winter, meaning that he had to be kept on the active roster (or the 15-day DL) for the duration of the year for the Phillies to retain his rights. He was only recently activated after serving an 80-game PED suspension, and evidently didn’t show enough to warrant a roster spot.
It’s a short sample, but the numbers certainly weren’t there for Stumpf. He allowed six earned runs on nine hits and two walks, while recording just a pair of strikeouts, in five frames over seven total appearances on the year.