MLB

Yankees need to define Joba Role

TAMPA — Joba Chamberlain has stuffed a lot into 281 2/3 major league innings.

He has been phenom and frustration, starter and reliever, heir to the top of the rotation and heir to Mariano Rivera.

Forget the Joba Rules, we have to deal with the Joba Roles. He has played more parts than Kevin Spacey.

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Yet we still don’t know who he is, character actor or star. You probably wouldn’t be shocked if he re-emerged as the best eighth-inning man in the majors or if he erratically pitched himself back to Triple-A. Both his fastball and his career have flammable qualities.

And let’s not even get on the subject of the future. No one is ruling out that Chamberlain will again be in play for the 2011 rotation. Heck, general manager Brian Cashman said he could see scenarios in which Joba works as a starter this year.

“A little, yeah,” Chamberlain said when asked if he would like the Yankees to firmly declare what he is so he can settle into his career. But then Chamberlain switched into his more familiar clichés about doing what is best for the team and still being young and learning. He said it is not time yet to confront Yankees officials about identifying his role.

Perhaps that is because the Yankees are not completely sure. Phil Hughes is the fifth starter, but the Yankees will not even say Chamberlain is the eighth-inning guy. There is a simple reason for that. They don’t trust him. They think Chamberlain tends to get too comfortable too quickly, and they want to keep him motivated, keep a carrot dangling.

Chamberlain almost certainly will pitch in the eighth inning when the season opens, but what happens next is unclear. Part of it has to do with Chamberlain, part probably has to do with the makeup of the team moving forward. Does Mariano Rivera begin to falter at age 40, moving the Yankees to project Joba as Mo’s successor?

Does Hughes stumble in the rotation or does Andy Pettitte finally retire or does Javier Vazquez leave as a free agent? If any of that occurs, the Yankees could be trying to stretch out Chamberlain again to start.

At this moment, all the maneuvering the Yankees put into the Joba Rules, especially the past two years, feel like a bit of a waste with Chamberlain back as a reliever. Cashman vehemently disagrees. In fact, nothing quite unsettles Cashman’s even temper like the never-ending debates about Chamberlain’s usage patterns.

Cashman knows the least controversial move would have been to simply let Chamberlain have a normal minor league apprenticeship as a starter. Instead, the Yankees weighed that against the big-league team’s needs. So Chamberlain was summoned as a reliever in 2007, which was instrumental to making the playoffs. And the Yanks let Joba build up his innings in the majors the past two years, and it did not prevent a championship campaign in 2009.

Cashman argues that if Chamberlain had the first full season as a starter for anyone else that he had for the Yankees last year — some good, some bad, a lot of working out kinks — it would have been viewed as normal progression and good enough to return to the rotation this year. But the Yankees went out and got Vazquez as a fourth veteran starter and determined they preferred Hughes in the rotation over Joba before spring even began.

There is much that the Yankees like about Hughes, including that temperamentally he is more trustworthy than Joba. Is he better than Chamberlain? That is still to be determined and why the Yankees are trying to keep an open mind about both pitchers’ futures.

That is why the Yankees would not have an answer, even if Chamberlain did come seeking one. The organization doesn’t know where he fits. They still don’t know who he is in every way. So maybe that is the most important Joba Role this year for Chamberlain, reaffirming not only his talent, but also his reliability.

joel.sherman@nypost.com