SAN FRANCISCO -- Don't know who Daniel Ray Herrera is? Look for the diminutive pitcher throwing the baseball in the wrong direction.

That would be a screwball, Herrera's go-to pitch.

"There's not a lot of people around the league that throw it, especially being left-handed," he said. "It's just a different look, different look that hitters have to see."

The Reds reliever gained an affinity for the rarely seen pitch when, as a starter at the University of New Mexico, he was attempting to learn how to throw a changeup. Knowing full well short pitchers have short careers, the 5-foot-6-inch Herrera was looking for a complement to his below-average fastball. He found something else, simply through trial and error.

"It really didn't act like a changeup anymore," he said. "[The pitch] was screwballing. I started throwing it in college and it's worked for me ever since."

Herrera, drafted by the Texas Rangers in 2006 and sent along with Edinson Volquez to Cincinnati in the 2007 trade for Josh Hamilton, led the Reds in appearances (48) entering Sunday, when his team completed its series with the San Francisco Giants.

He won his first Major League game June 16 and has notched a 2.64 ERA thus far in 2009.

"I feel good about the production I've had this year," he said. "Our job as a bullpen is to keep us in the game and, for the most part, I feel like I've done that."

Literally offering a spinning contrast to his slider, Herrera's screwball uniquely breaks away from a right-handed hitter (and toward a lefty). The 24-year-old credits his flexible fingers for the offering few others in recent memory have employed. Jim Mecir featured the pitch for 11 seasons (1995-2005) in the big leagues. More recently, the Oakland A's Dallas Braden was encouraged not to throw it, for fear of injury.

It's working for Herrera. He hasn't allowed a run in 10 of his last 11 appearances.

In his last full inning of work, Monday against the Chicago Cubs, his fastball topped out at 87 mph and his slowest screwball was exactly 20 mph slower. That doesn't even include his second breaking ball, which is often in the mid-70 mph range.

"I'm not throwing hard," he said. "Mixing [in] different speeds is my game."

That explains, at least in part, why he's surrounded in Cincinnati's bullpen with more lively arms. Led in the late innings by veterans Francisco Cordero and Arthur Rhodes, the Reds were third in National League bullpen ERA (3.57) entering Sunday.

"I get to hang out with Arthur and [David] Weathers," he said about an hour before Weathers was traded to the Milwaukee Brewers. "These guys have a lot of experience, and it's fun to learn off them."

Both have spoken with Herrera about how to attack hitters, especially Rhodes, who's been getting left-handers to make outs for 18 seasons.

One thing they won't be teaching him, though: how to throw a screwball.