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08/25/11 12:10 AM ET

Black keeping an eye on Gregerson

SAN FRANCISCO -- Padres left-hander Luke Gregerson is struggling with his slider, said his manager Bud Black, who would know things like that.

Gregerson, who set a Major League record with 40 holds last year, suffered a blown save Tuesday night in the Padres' 7-5 win over the Giants, giving up hits to three consecutive batters before he was relieved without getting an out.

"His inconsistency is something to be concerned with," said Black, a left-hander who spent 15 seasons the big leagues. "We're seeing flashes of at bats which are very good. He's a fastball-slider-type pitcher, and his slider has not been as consistent as it was in 2009 and 2010."

Gregerson (3-3, 3.11 ERA) was moved into the eighth-inning role after Mike Adams was traded. He's seen his ERA grow from 2.37 on July 7.

"I don't know if the inconsistency stems from taking on more of a role," Black said. "The ball is just not spinning as consistently. He needs to get back to spinning the ball."

While his ERA is lower than it has been, he only has 13 holds to date (he had 32 at this time last year) and seven of those have come since Aug. 9.

Rick Eymer is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.