TUCSON -- Clay Zavada is not developing a curveball as much as he is rediscovering it.

The D-backs southpaw has been working on his curve this spring in hopes of improving his effectiveness against left-handed hitters, who batted .284 against him during his rookie campaign last year.

The 25-year-old, who was called up in May, held right-handers to a .205 mark thanks to his signature changeup.

"I actually had a really good curveball in college," Zavada said. "I just got away from throwing it."

Zavada did not start throwing his changeup, which manager A.J. Hinch has likened to a "Bugs Bunny changeup" for the way it gets hitters off balance, until he was with Rookie League Missoula in 2006.

With a scarcity of lefties at the Major League level, it would be nice for the D-backs if Zavada could improve his efficiency against left-handed hitters.

"I know my numbers weren't very good against them last year," Zavada said. "But I did get better at the end of the year against them. I can throw my changeup to lefties. I struck out Adrian Gonzalez on one, I got Prince Fielder on one. It's just a matter of finding the best balance of pitches."

So far, pitching coach Mel Stottlemyre has been impressed with what he's seen of Zavada's curve.

You wouldn't know it judging by how frustrated Zavada looks sometimes when he's working on it.

"That's because he'll throw a good one and then wants to throw another even nastier one," Stottlemyre said.

Zavada admits that his patience has not been good.

"I just need to take a deep breath, chill out and believe in it," he said. "It's there."