The Mets' best first-half pitcher, Niese has been on the DL since July 5 with what the team termed a left shoulder strain. A subsequent MRI revealed inflammation in the A/C joint of his shoulder.
Niese, who missed significant time this spring with shoulder and elbow issues and began the season on the DL, was 5-4 with a 2.96 ERA in 17 starts between injury stints.
Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDicomo. This story was not subject to the approval of Major League Baseball or its clubs.