He had a three-run homer and an RBI double Monday night as the Athletics' offense came to life in a 12-6 victory over Los Angeles.
"I'm still tweaking it, just trying to find a consistent approach up there," said Piazza, who came off the disabled list last Friday. "I'm seeing the ball a little better, though. I was fortunate to at least not miss a couple of pitches to hit early on and get us going a little bit.
The 38-year-old Piazza, who went on the DL on May 3 after spraining his right shoulder in a home plate collision the previous day, is being used at DH by the Athletics. But it's unclear how often he'll play there, since Jack Cust has been swinging the bat well and isn't thought of as an everyday outfielder.
"You can't worry about whether you're playing or not playing," he said. "You just try to get good pitches to hit when you're out there and hopefully kind of force the issue a little. That's all you want to do, make decisions hard for the manager."
The fourth-inning homer off Dustin Moseley was Piazza's second of the year. His other came on April 5, also in Anaheim -- a tiebreaking solo shot against closer Francisco Rodriguez in the ninth inning of a 4-3 victory.
Mark Ellis added a pair of solo homers and had an RBI double for the A's, who won for the third time in 14 games.
The A's rocked an ailing Bartolo Colon for four runs in the first inning, then scored at least one run in each of the next five innings to take a 12-5 lead.
Colon (6-6) left after the first because of soreness in his right elbow. The 2005 AL Cy Young winner, who won his first five decisions this season but is 1-6 over his last 10 starts, will be examined on Tuesday.
"It bothered him warming up, but he wanted to pitch. In the first inning, he was just spinning his wheels," Scioscia said. "We're concerned. It's in a different spot than what we were dealing with before. We'll see where we are tomorrow."
Colon previously was bothered by triceps tendinitis in his right arm.
Joe Kennedy (2-9) pitched two scoreless innings and allowed one hit to earn the win. It was his first victory in 10 career decisions against the Angels.
A's starter Chad Gaudin had control problems, walking six, including two with the bases loaded in the fourth inning. He lasted 3 2/3 innings, giving up five runs and six hits, including Mike Napoli's solo homer, his ninth, in the second.
The Athletics had scored more than three runs only three times since July 2. They came up with 13 hits against the Angels.
"They looked like a team that was well-oiled offensively," Scioscia said. "They got a ton of hits, got two-out hits, hits with runners in scoring position."
The 30-year-old Ellis, in his sixth major league season, had his first multihomer game and extended his errorless streak to 58 games, equaling his career high set last year. He's the only second baseman in Oakland history to have two such streaks of 50 or more games.
He didn't realize he had tied his personal mark.
"It's not one of those things I keep track of, but every once in a while somebody says something about it," Ellis said. "That means a lot to me. I pride myself on defense, and I think that's the reason I'm here. I'm not here in the big leagues to be a home run hitter."
He had an RBI double in the first inning, homered off Moseley in the third, then added his 11th homer of the year off Chris Bootcheck in the sixth.
Shannon Stewart had two hits, scored twice and drove in a pair of runs for Oakland.
Colon threw 33 pitches and gave up four hits and a walk, with one walk and one strikeout. It was the fourth time in his career he's pitched one inning or less.
Scioscia said Colon always had been a workhorse on the mound, and the problems, "It's baseball. It's what happens to pitchers. I know Bart's disappointed."
Moseley gave up five runs and five hits in 2 2/3 innings.
- Oakland RHP Huston Street, who was activated from the DL after missing 63 games, pitched one inning and allowed a run and two hits. He was sidelined because of an irritation in his right ulnar nerve.
- Napoli's home run in the second inning was the first given up by an Oakland starter in 11 games since the All-Star break.