PHILADELPHIA -- Jonathon Niese faces an uncertain future after doctors discovered a partial tear in the rotator cuff of his left shoulder Friday.
For now, doctors have advised the Mets lefthander against surgery in favor of a strengthening program, according to assistant general manager John Ricco. But in two weeks, Ricco said, doctors will perform another MRI, which will determine what comes next.
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If the tear shows signs of healing, Niese, who was placed on the disabled list, will continue non-surgical rehabilitation. Ricco said the Mets believe the tear is not "significant," leaving open the possibility of avoiding surgery that could sideline Niese for at least a year.
If the tear shows no signs of healing, the Mets may have no choice but to send Niese for a procedure that will alter the trajectory of his career.
"I'm not going to speculate beyond that," Ricco said of Niese's next exam. "We have a plan for the next couple of weeks. We'll see how that goes. We'll have more information."
Even if Niese avoids surgery, he will face a difficult road back. When it comes to pitching injuries, shoulder problems are considered more severe than elbow woes. Shoulder injuries typically carry more uncertainty in terms of prospects for a full recovery.
The Mets already have experienced the devastating effects of a major shoulder injury. Surgery earlier this season effectively ended Johan Santana's career with the Mets.
With Santana out, Niese stepped in as the Mets' Opening Day starter, an honor he earned with a breakout 2012 season in which he went 13-9 with a 3.40 ERA. He also set a career high by throwing 1901/3 innings.
The 26-year-old entered this season as part of a bright core of starting pitchers that now includes Matt Harvey and Zack Wheeler. Manager Terry Collins repeatedly has called Niese a key piece in the team's efforts to build a winner.
General manager Sandy Alderson reinforced Niese's standing in the franchise's eyes, locking him up with a five-year, $25.5-million contract in April 2012.
Aside from David Wright's extension, the deal is the longest commitment the Mets have made to a player during Alderson's tenure as a general manager. But the team-friendly contract likely would have given the Mets the flexibility to use Niese as a trade chip had they so chosen.
"I think that he kind of slides right into that plan that everybody talks about," Wright said this week. "You talk about the electric stuff of both Harv and Wheeler, but then Niese I think is a front end-type guy . . . if he's healthy and he's right."
But Niese rarely has been either of those while going 3-6 with a 4.32 ERA this season. His body failed to bounce back after he pitched in subfreezing temperatures earlier this season. He eventually battled through shoulder tendinitis -- among other ailments -- that forced him to miss one start.
On Thursday, Niese felt pain while pitching to the Braves' Tyler Pastornicky in the fourth inning. After throwing a few more pitches, he signaled for trainers.
Niese left the game without attempting to throw a warm-up pitch -- a hint of the trouble to come.