A year ago, Westbrook said, he was mainly tipping the breaking ball, which is mainly a change of pace delivery for him.
"If they know a breaking ball is coming they know not to swing at it," he said. "They can sit back, see it, or take it."
Westbrook allowed an unearned run in seven innings in his first start of 2012 at Cincinnati, and one run in seven innings against the Cubs in his second start.
He was ahead in the count most of the time in his second start, throwing first-pitch strikes to nine of the first 11 hitters, and counting a double play accumulated 13 groundball outs.
"It was just ground ball out after ground ball out, and he backed it up with a little cutter and little slider," the Cubs' Joe Mather said. "We didn't have enough good at-bats until the middle of the game."
Westbrook had trouble finding the strike zone early in his 2012 debut because he was "all geeked up." In his second start, it was strike one all day long.
"I felt good about where I was from the first inning on," Westbrook said. "I'm just trying to continue on with that whole format."
Westbrook isn't sure exactly how the new diet is helping the sinking fastball that he pounds at hitters when everything's working, although he's been able to be more precise with his mechanics. He definitely feels lighter on his feet, and that combined with the results has boosted his confidence.
As for his pants size, Westbrook hasn't lost a couple of inches because the uniforms have a new design.
"Actually, it's the same," he said. "These new pants are a little tighter this year, but that's OK. I don' mind it."