The New York Mets placed struggling right-hander Jeremy Hefner on the 15-day disabled list with a partially torn MCL in his pitching elbow on Wednesday.

Hefner had been complaining of lingering pain in the affected area, with the 27-year-old pitching to an 0-2 record and a 9.13 ERA in five starts since the All-Star break. An MRI taken on Wednesday revealed the extent of the injury.

His move to the disabled list is retroactive to Aug. 10. He had been optioned to Triple-A Las Vegas on Sunday in order to open up a roster spot for pitcher Jonathon Niese.

Hefner has started all but one of the 24 games he's pitched in this season, accumulating a 4-8 record with a 4.34 earned run average.