Marinaccio will be placed on the 15-day injured list with shoulder inflammation, Erik Boland of Newsday reports.
Manager Aaron Boone described the issue as "dead arm" earlier Saturday. The diagnosis has changed, but either way, Marinaccio's excellent rookie season will be put on hold for at least a couple weeks. Marinaccio threw a scoreless inning in the first game of Saturday's doubleheader and now has a 2.33 ERA and 0.88 WHIP in his first 17 MLB appearances.