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01/27/11 2:03 PM EST

Joba's dip in velocity traced back to '08 injury

Yankees view right-hander strictly as reliever going forward

NEW YORK -- The Yankees' decision to end the Joba Chamberlain debate with a bullpen assignment has seemed final for some time, but the organization had guarded its most specific reasons until this week.

One of the many topics discussed by Yankees general manager Brian Cashman over the last few days was an acknowledgment that Chamberlain has not been the same since suffering a right shoulder injury in August 2008, which is why the team views him strictly as a reliever.

Cashman has touched upon Chamberlain's physical situation in the past, but these were the clearest terms used to date in tracing why Chamberlain's velocity has dipped from when he stole headlines as a phenom right-hander.

"Since the injury in Texas, his stuff is different now," Cashman said. "We've seen over time that his stuff plays so much better as a reliever since he hurt his shoulder."

Now 25, Chamberlain started 2008 in the Yankees' bullpen under the heavy scrutiny of the "Joba Rules." He transitioned to the rotation in June, making his first 12 big league starts and showing promise by going 3-1 with a 2.76 ERA.

On Aug. 4, 2008, Chamberlain came out in the fifth inning of a 9-5 loss at Texas with stiffness in his pitching shoulder. He was placed on the disabled list, returning for 10 September relief appearances before the season ended.

At the time, there was little outside thought that the injury would prove to be a significant setback for Chamberlain, who was selected as a high-end starting pitching prospect in the supplemental first round of the 2007 First-Year Player Draft.

Chamberlain made 31 starts for the Yankees in 2009, going 9-6 with a 4.78 ERA, but his velocity became an issue. Reporters quizzed manager Joe Girardi about the topic as the year went on, noticing that it no longer ticked into the high 90s as it had before.

Cashman no longer feels that dominant equipment exists in Chamberlain, and there is data to back up those beliefs. According to the Web site Fangraphs.com, Chamberlain's fastball lost 2.5 mph as a starter from 2008-09, with the percentage of swinging strikes dropping from six to three.

His slider, a dominant out pitch, slid from 25 percent swinging strikes to 20 percent. Overall, Chamberlain's strikeouts dropped from 10.2 per nine innings as a starter in 2008 to 7.6 in '09.

The Yankees gave Chamberlain one last chance to pitch in the rotation last year, but he lost a Spring Training battle with Phil Hughes to serve as the fifth starter, making a team-leading 73 appearances out of the bullpen.

And that, it would appear, is where he will remain. The Yankees decided Chamberlain belonged in the bullpen before they broke camp and have remained consistent with that stance, even though the team's greatest need continues to be starting pitching.

Cashman said this week that it is clear Chamberlain's stuff becomes "watered down" by starting, given the sample sizes already seen. But that does not mean the Yankees can't see a future for Chamberlain.

Having resisted trade offers for the hurler this winter, Cashman said the Yankees believe Chamberlain's value would be higher by being part of the relief hierarchy leading to closer Mariano Rivera.

"I've answered the Joba thing enough," Cashman said. "I think everybody knows the answer to that. Joba is in the bullpen, and I think everybody is happy with that."

Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.