Chamberlain pitched only 88 1/3 innings in the minors before he joined the Yankees in August 2007. He entered this season with 124 1/3 innings in the majors and can match that total for this season with just eight outs in his next start.
"We're just trying to be smart about it," manager Joe Girardi said. "We're not trying to overwork him his first time in a rotation for the whole year. There are instances where players have thrown 200 innings that weren't accustomed to that and have had struggles after.
"There's a history that has been studied by our people and this is what we feel is best," he said.
Girardi said Chamberlain will get the ball next Wednesday at Oakland. Newly acquired Chad Gaudin or Sergio Mitre will start this weekend against the Seattle Mariners, with the day depending on what New York needs out of its bullpen over the next couple games.
Girardi said he was leaning toward Mitre on Saturday after Gaudin worked two scoreless innings in New York's 4-3, 11-inning victory over the Toronto Blue Jays on Wednesday. Gaudin got the win in his Yankees debut.
Chamberlain went eight days between starts over the All-Star break and responded with 6 2/3 sparkling innings in a win against Detroit on July 19. He worked on regular rest in each of his next two outings, allowing just one run over 15 innings in victories over Oakland and Tampa Bay.
Then came a shaky outing against the Boston Red Sox on seven days' rest and another so-so performance against Toronto, when he allowed four runs and five hits over six innings in a no-decision.
"It's tough, what he's been going through," catcher Jorge Posada said after New York's 7-5 victory over the Blue Jays on Tuesday night. "He doesn't know when he's going to pitch. It's tough to really mentally put it altogether. I think he's doing everything he can to stay focused, but it's tough."
Chamberlain, who turns 24 in September, is 4-0 with a 2.76 ERA in his last five starts and hasn't lost since June 18 against the Washington Nationals. He is 8-2 with a 3.85 ERA in 22 starts on the year.
New York also closely monitored his innings when he reached the majors two years ago.
"As a competitor, you want to be out there with your teammates all the time fighting and clawing," Chamberlain said, "but I also understand I want to do this for a long time and not just a couple years. So you have to keep that perspective. I've learned to become patient over the last couple years being here."
The Yankees have mapped out Chamberlain's schedule for the rest of the season and Girardi lets him know when his next start will be after each outing, preventing him from looking ahead too much.
"I always want him to focus on that start," Girardi said before the Yankees' victory over Toronto on Wednesday.
Girardi insisted the plan for Chamberlain doesn't include a return to the bullpen and will not be altered if he struggles. He was also clear when asked if the right-hander would be "fully available" if the AL East-leading Yankees reach the playoffs.
"All hands on deck," he said.