The Nationals placed Parker on the 15-day injured list Monday with left elbow inflammation.
Parker was forced from an appearance Sunday versus the Orioles due to the injury. While the injury designation is listed as inflammation, it's not clear whether Parker might still need to undergo testing to rule out a more serious injury. The southpaw has collected a 6.58 ERA and 34:13 K:BB over 39.2 innings out of the Washington bullpen this season.