TAMPA, Fla.—Just like last year, one out of every four or five pitches A.J. Burnett threw Monday against the Phillies was imperfect. It didn't go where he wanted it to.

Unlike last year, he didn't care.

"It's getting there, it's getting there," Burnett said. "There's still that one out of every four, but the difference is, I'm not thinking about it, I'm not wondering why that one out of every five, or one out of three, happens. It's just get the ball back and go."

Burnett threw three perfect innings Monday against the Philadelphia Phillies, giving him five shutout innings so far this spring. He retired five by groundout, three by fly out and Ryan Howard by strikeout.

The mechanical changes he's trying to make seem to be working—and when they don't, he doesn't lose focus.

His new catcher, Russell Martin, didn't see Burnett pitch last year, and has only heard the horror stories. He didn't see a shred of that dysfunction in the pitcher on the mound Monday.

"All I know is what I'm seeing right now, and he looks pretty good. The past is done," Martin said.

This looked nothing like a pitcher who had a 5-plus ERA and lost 15 games last season, Martin said.

"Not at all. He had ace stuff today. His fastball was effortless, and he looks like he has even more if he wants it. He's under control with his delivery, and he looked like he had fun out there today. "

Burnett seemed to improve the further he got into the game. Against the last batter he faced, Wilson Valdez, Burnett fired five fastballs down and away, all perfectly spotted. Valdez fouled one after another away, then finally went down on a ground ball to the shortstop. Every pitch was in just the right location, and the repetition didn't jar Burnett into bad mechanics.

"When my mind's clear and I'm not thinking about this or that, it works," Burnett said.