Even during a week that may stand as the best of this 2013 season, the Mets cannot avoid a trip-up. Jon Niese, the team’s Opening Day starter, will miss his scheduled start tomorrow due to shoulder tendinitis. The left-hander said his shoulder has bothered him over his last four starts, affecting his recovery and inhibiting him from throwing strong bullpen sessions. Manager Terry Collins said he was first approached by Niese two days ago. Niese said that it became so bad he was unable to throw a bullpen Wednesday. The tendinitis left Niese sore and he attributed the inflammation in his shoulder to it as well. He had an MRI yesterday that revealed there was no structural damage. While Niese said he "could probably" pitch Saturday, he decided to eschew the risk and shut it down. The move was made for precautionary reasons. The feeling is that taking time off — Niese will rest completely for 3-4 days — will allow the tendinitis to dissipate. Continuing to pitch may force the injury to linger. "I just didn’t want it to get progressively worse," Niese said. This as Niese comes off of his best start of the season, when he allowed one run in seven innings in a victory over the Yankees Monday. Niese’s last four starts have been an interesting stretch. Though he allowed eight runs in 4⅓ innings on May 11, he followed it by allowing just three runs over his next 20⅓ innings. He watched his ERA dip a run-and-a-half to 4.40. Collins said Niese was particularly bothered by the tendinitis during his last start, but still considered pitching Saturday.