One Step Back for Mets" Staff as Niese Is Hurt PHILADELPHIA - The Mets this week seemed to be accelerating faster than ever toward their often-discussed but still-hypothetical future, when a successful club will coalesce around a young pitching staff. Matt Harvey, 24, led the charge on Tuesday afternoon, dominating a division rival and cementing his status as baseball's hottest young pitcher. Zack Wheeler, 23, was electrifying later that night in his major league debut. But the organization's vision of the future blurred for the moment on Friday afternoon when Jon Niese, the team's opening day starter this year, was found to have a partially torn rotator cuff. "This is huge for us," Manager Terry Collins said before the Mets" 4-3 victory over the Philadelphia Phillies. Jon Niese was our No. 1 guy coming out of spring training. This does not help us. John Ricco, the Mets" general manager, said the tear was discovered through a magnetic resonance imaging exam on Friday, the day after Niese was pulled from a game because of discomfort around his shoulder. Niese, a 26-year-old left-hander, was placed on the disabled list. He will rest for two weeks and then have another M.R.I. exam, at which point the team doctors are expected to make a recommendation on whether surgery is necessary. The Mets hope a procedure will not be necessary. Rotator cuff injuries - shoulder ailments as a whole, really - are considered ominous. The rotator cuff refers to the muscles that move the shoulder; the tendons that connect the muscles to the bone are susceptible to tearing. For some athletes, surgery can be avoided if the surrounding muscles are strengthened to the point that they can compensate for the weakened tendon. Pitchers who resort to rotator cuff surgery generally require several months to return to game form. Ricco said the team doctors believe Niese's partial tear could be small enough that surgery will not be needed. Furthermore, the doctors indicated that the tear could start to heal on its own. Ricco was unwilling to offer a best-case return date. "He's going to rest for two weeks and I'm not going to speculate beyond that," he said. We have a plan for the next couple of weeks, and we'll see how that goes. Niese missed a start earlier this month after he was found to have shoulder tendinitis. An M.R.I. administered on May 30 revealed no structural damage. After skipping one rotation turn, Niese came back to pitch twice before Thursday's outing, when he said he began to experience pain again. According to Ricco, the current tear occurred sometime after the initial first test. "This is something that changed," Ricco said. The Mets will now be without a starter they expected to help lead the rotation this year and into the future. The front office, which has been reluctant to dole out long-term contracts, made its opinion about Niese clear early last year, when they signed him to a five-year deal worth $25 million. Early this year, after R. A. Dickey, who won 20 games for the Mets last year, departed and before Harvey ascended to his current lofty perch, Niese was briefly considered the team's ace. He took the ball for the season opener at Citi Field. But since then, he has not performed to expectations, compiling a 3-6 record and 4.32 earned run average. His struggles could be attributed partly to the tendinitis, which plagued him for four starts this spring. But he claimed that he felt healthy after the one outing he skipped. After Wheeler's rise this week to the major leagues, the Mets were planning to employ a six-man rotation for the near future. Collins said he hoped it would give each starter some additional rest heading into the season's second half. That will not be possible now. The Mets on Friday recalled Greg Burke, 30, a right-handed relief pitcher, to take the open roster spot. Niese has been known for his durable arm and smooth mechanics, and Collins was asked whether Dan Warthen, the pitching coach, had noticed anything about Niese's motion that may have caused the injury. "I asked Dan about that today, and Dan said he's going to look at some tapes," Collins said. But he didn't think there was anything wrong with his delivery. Either way, Niese's actual pitching motion seems like a faraway concern now. The Mets need to wait two weeks to see when he can even begin to use any pitching motion again.