Source: Mets' Wheeler (shoulder) headed to IL

New York Mets right-hander Zack Wheeler will be placed on the injured list with shoulder fatigue, a source familiar with the situation told ESPN, a significant blow to his trade value as the July 31 deadline approaches.

Wheeler, 29, was among the most sought-after pitchers on the trade market, with contenders believing he would cost less in prospect capital than pitchers with club control. Wheeler will become a free agent after the 2019 season.

Still, because the interest in him was significant -- teams believed that with slight adjustments, he could regain his dominant 2018 form -- the Mets hoped Wheeler could return a strong prospect package.

Questions now about his shoulder will put a dent in that. Wheeler will be eligible to return from the injured list July 23, which would give him time to make two starts and re-establish some value. One general manager who had interest in dealing for Wheeler told ESPN: "Not anymore."

The Mets, 42-51 and six games back of the second wild-card spot but with eight teams ahead of them, are in something of a precarious position when considering how to play the deadline. They've entertained the idea of trading starter Noah Syndergaard in addition to pursuing deals involving infielder Todd Frazier and starter Jason Vargas, both of whom will be free agents at the end of the season. The price for Syndergaard, according to sources, remains too high to call a deal likely.

In past years, the injury to Wheeler might not have been as acute. The Mets could have dealt him during the August waiver-trade period. Major League Baseball got rid of August trades this season, settling on the single July 31 deadline.