BOSTON (AP) – Red Sox rookie Clay Buchholz won’t pitch for the rest of the year and will miss the postseason because of shoulder fatigue.

The 23-year-old right-hander pitched a no-hitter against Baltimore on Sept. 1 in his second major league start, then was sent to the bullpen and made a relief appearance on Sept. 6. He had just one outing after that, starting and losing at Toronto on Sept. 19.

“It was disheartening at first, but I don’t think anybody expected me to be up here,” Buchholz said Friday. “I think I’d be more down about it if I started the year here and it came up now.”

General manager Theo Epstein said the club had learned to be cautious following an injury to closer Jonathan Papelbon last year.

Boston wasn’t comfortable will Buchholz’s last bullpen session last weekend.

Buchholz pitched 125 1-3 innings in the minor leagues thus year, going 7-2 with a 1.77 ERA for Double-A Portland and 1-3 with a 3.96 ERA at Triple-A Pawtucket. He is 3-1 with a 1.59 ERA in 22 2-3 innings for Boston.

“I’m going to get home, take a few days off and start working towards next year,” Buchholz said. “The key is to get to spring training, get healthy and try to fight for a role in the starting rotation.”

The club felt it was best for him to end his season immediately.

“Unfortunately, he can’t pitch safely right now” Epstein said. “He’s at the point similar to where Papelbon got last year.”

Papelbon didn’t pitch after feeling discomfort in his right shoulder against Toronto on Sept. 1 last season. The Red Sox brought him to spring training as a starter, thinking pitching every fifth day would lessen stress on his shoulder. He returned to the closer role late in spring training, and the team has been careful not to overwork him.

“I think going through Pap we have a good understanding.” Epstein said.

“Pap was simply overused (last year),” Francona said. “When you get overused, there’s fatigue and a chance for injury. That was my mistake.”

Buchholz threw 115 pitches in his no-hitter, 21 more than he threw in any Triple-A game this year.

“Innings-wise, he was OK,” Francona said, but “we don’t put a pitcher out there if we have some concerns. We actually did not have him throwing the last five or six days.”