© 2009 MLB Advanced Media, L.P. All rights reserved.

09/24/09 10:03 PM ET

Affeldt enjoying breakout season

Lefty sports lowest ERA among National League relievers

SAN FRANCISCO -- It could be said that Jeremy Affeldt has excelled at staying grounded this season.

Regardless of what happens in the season's final 10 games, Affeldt has sustained his best year by far since breaking into the Major Leagues in 2002. The left-hander entered Thursday with a 1.72 ERA, lowest among National League relievers, in 70 appearances. That ERA is nearly half of his previous best, which was 3.33 in 74 games last year with Cincinnati.

Prompting harmless ground balls has helped Affeldt, who has limited opponents to a .201 batting average. Through 2008, his grounder-to-fly-ball ratio was 1.09-to-1 -- essentially a 50-50 split. This season, however, Affeldt's grounder-to-fly-ball ratio is 2.02-to-1, largely accounting for the Major League-leading 16 double plays he has induced.

Versatility has furthered Affeldt's success. He has found that he can prompt grounders with either his curveball or his two-seam fastball, which has sinking action.

Late movement is the key to any effective pitch, and such is the case with Affeldt's curve.

"The later the curveball snaps, the better chance you'll have of getting a ground ball," he said.

Affeldt has continued to gain command of the two-seamer, which he picked up last season from right-hander David Weathers when both played for Cincinnati. Affeldt said that he has gained enough confidence to throw it when he's behind on the count, adding, "I think I throw it in the [strike] zone enough to where if they make contact, it's going to be a ground ball."

Affeldt has been particularly efficient lately. In his last 14 appearances before Monday, he had allowed one earned run in 10 2/3 innings.

Though the Giants have received criticism to varying degrees for many of their free-agent signings, such as Barry Zito, Aaron Rowand and Edgar Renteria, nobody has questioned their deal with Affeldt, who signed a two-year, $8 million contract last offseason.

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