"Diamondbacks pitcher Zach Duke isn't undergoing any major changes this spring. No new pitches, no different delivery.

He is coming off the worst season of his career but says he already possesses everything he needs to be a good major-league pitcher. He's done it before - and believes he'll do it again.

"I have the tools," he said. "I know I have the tools. They're in there. I believe I can be a very good pitcher. I have been in the past. I know it's in there. The whole thing for me is allowing it to happen."

That didn't happen last season with the Pittsburgh Pirates, which mostly explains why he's standing in the Diamondbacks' clubhouse at Salt River Fields. In his sixth season with the Pirates, Duke posted a career-worst 5.72 ERA, prompting the Pirates to designate him for assignment in November, leading to his trade to the Diamondbacks.

A year earlier, he was an All-Star - and not just an obligatory, one-representative-per-team type. At the break in 2009, he had a 3.29 ERA and was selected by Phillies manager Charlie Manuel as the Pirates' second representative for the game.

But 2010 was a different story.

"There were times when I got inside my own head and tried to do too much and ended up having the opposite effect," Duke said. "I was trying to make a better pitch than what I could make. You put more effort in, and it ends up being a borderline pitch that doesn't have as good of movement and ends up right down the middle. It just comes from pressing on myself a little bit and trying to do more than I can actually do.""