MLB

IN JOBA MATH, LESS MEANS MORE

IN the Bizarro World that Joba Chamberlain inhabits, the better he pitches, the fewer times he’ll get the ball, while the worse he pitches, the more starts he’ll get between now and the finish line.

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It’s the innings, stupid, and no, the pejorative is aimed neither at Chamberlain nor at Joe Girardi, the manager whose task it is to steer the Yankees to the playoffs while constructing a starting rotation that accommodates the latest edition of the Joba Rules.

Girardi on Monday said that the Yankees’ plan for Chamberlain, who will be capped at no more than 160 innings in the regular season, “is mapped out.”

Last night, the manager revealed that the map would not include a detour to the bullpen. Instead, Girardi said that Chamberlain would come off his regular spot in the five-man rotation and have his starts staggered the rest of the way, beginning the next time through.

“We have no plans to put him in the bullpen,” the manager said before Chamberlain navigated through six uneven innings in the 7-5 victory over the Jays. “There are going to be times when he goes on the fifth day and there are other times where he might get a little extra.”

Truth be told, there are going to be times when Chamberlain is going to have to get a lot of extra rest in order to make the arithmetic work. There are 39 innings at most remaining in the pinstriped reserve, with 49 games and 54 days remaining in the season.

That equates to six more starts if Chamberlain pitches reasonably well, five if he’s exceptional and seven or eight if he gets knocked out early a few times. This equates to a unique burden on Chamberlain even as the Yankees do everything in their power to limit the burden on his 23-year-old right arm.

“It’s tough for him to put it together mentally when he doesn’t know when he’s going to pitch,” said Jorge Posada, whose eighth-inning home run completed a back-to-back with Hideki Matsui that brought the Yanks back from a one-run deficit. “He’s doing everything he can to retain his focus.”

Chamberlain was dominant in his first three starts following the All-Star break, allowing two runs in 21 2/3 innings. But he struggled through five innings on seven days’ rest against the Red Sox last Thursday, and was erratic last night, though he did retire nine of the final 10 Jays he faced after yielding three runs in the third and a leadoff homer in the fourth.

“You can look at the small picture of the third inning or the overall six,” said Girardi, whose team is 32-11 since June 24. “He had a bad inning, he wasn’t horrible, and I still think he threw the ball really well. He lost it and then he found it.

“Joba is still a work in progress. He’s a young man at a point in his career that he’s never been to [in terms of innings].”

After today against the Jays, the Yanks have four in Seattle, three in Oakland and three in Boston. Chamberlain would ordinarily start next on Sunday against the Mariners, but not now. Chad Gaudin will take that turn.

Girardi would not announce when Joba would pitch next, but it’s likely that the manager will manipulate the rotation so that Andy Pettitte, A.J. Burnett and CC Sabathia are lined up for the three at Fenway, Aug. 21-23. That would get Chamberlain back on the mound a week from today against the A’s.

“I understand that it’s a process and that there are ways to make the best of my days off by going to the weight room, watching video, doing whatever to improve,” Chamberlain said. “I want to be out there competing with my teammates, but I understand that I have a long time and that I have to be patient.

“I can’t be mad at it. I just have to be patient. I’ve had to be patient my three years here.”

Rules. Can’t live with them, can’t live without them in Bizarro World.

larry.brooks@nypost.com