New York Yankees relief pitcher Joba Chamberlain #62 watches the...

New York Yankees relief pitcher Joba Chamberlain #62 watches the game action from the dugout after giving up the game tying run in the top eighth inning against the Toronto Blue Jays at Yankee Stadium. (July 2, 2010) Credit: Newsday/Christopher Pasatieri

The date was June 30, 2009. The topic was the Yankees' eighth-inning guy - who at that moment was Brian Bruney.

"Bruney's our eighth-inning guy," manager Joe Girardi said. "We need to get Bruney going."

Ever wonder why general manager Brian Cashman always says bullpens are volatile? One year and 20 days ago, the Yankees trusted Bruney as their main setup reliever. He let a two-run lead get away in an eventual 8-5 win over the Mariners and lost his job within a week to Phil Hughes.

Bruney is still an eighth-inning guy. Only now it's for the Mets' Triple-A team in Buffalo.

Now the Yankees' eighth-inning guy is Joba Chamberlain (who, by the way, was the starting pitcher in that June 30 game).

But Chamberlain has been inconsistent all season; his ERA is 5.77 and he has allowed 59 baserunners in 39 innings.

On Saturday, Girardi seemed to back away from his commitment to Chamberlain as the main man ahead of Mariano Rivera, saying, "You have to earn your roles here and we evaluate it every day."

Chamberlain pitched in the eighth and ninth innings in Sunday's 9-5 win over the Rays. He struck out his first two batters, but Girardi brought in Rivera to get the last out after Chamberlain allowed a run in the ninth.

Don't look back, Joba. David Robertson, who has been very effective lately, might be gaining on you.

"Yeah, we're constantly evaluating everybody and we've had some inconsistencies in the entire bullpen other than Mariano," Cashman said Monday in a telephone interview. "I think we're still trying to feel our way. Basically, there are spots for people to earn or take if they want it or spots for people to lose. That's all. I think we have the personnel. I just think they haven't pitched as well as they have in the past."

Chamberlain, removed from the Joba Rules and not talked about as a No. 1 or 2 starting pitcher anymore, has been the biggest disappointment in a bullpen filled with poor performances and key injuries.

From Chamberlain to Chan Ho Park (5.90 ERA) to Alfredo Aceves and Damaso Marte (both on the disabled list) and, until recently, Robertson (5.01 ERA), the bridge to Mariano has been more like a crumbling footpath.

But no one is more important in that group than Chamberlain. And no one can be more baffling from outing to outing.

"He's been inconsistent at times," Cashman said. "Sometimes he's locked in and he's got the knockout stuff and there's other times that it's not there. The stuff he's got shows it's all there. It's just that we've got to get it in a more consistent manner."

Robertson, a favorite of Girardi, could get a look as the eighth-inning guy if Chamberlain falters. On Sunday, though, he was a surprise third-inning guy as the emergency replacement for Andy Pettitte, who left the game with a strained groin and will miss the next 4-5 weeks.

Robertson worked out of a bases-loaded jam and pitched 12/3 scoreless innings. Other than a July 2 outing in which he allowed four runs, Robertson has a 0.60 ERA in 15 innings since June 5.

"His stuff is terrific," Cashman said. "He struggled last year early, too. He might just be a late starter."

Notes & quotes: Cashman said he doesn't feel any added urgency to trade for a starting pitcher with Pettitte out. "This isn't a career-ending groin injury," he said . . . Sergio Mitre, who will replace Pettitte in the rotation Saturday vs. Kansas City, allowed two runs in 42/3 innings in his final rehab start for Triple-A Scranton/Wilkes-Barre. The Yankees will call up a different pitcher to replace Pettitte on the roster before tonight's game.

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