Parker pitched two scoreless innings in his first spring start Friday, a 13-9 Athletics' loss to the San Francisco Giants.
"I was trying to do way too much trying to make the team," Parker said. "I wanted to make a splash. This year I can prepare slower and smarter and that's a good thing."
Brandon Belt had three hits and drove in a run for the Giants, who scored seven times in sixth inning against reliever Travis Blackley.
Chris Young, in his first appearance in a week, added two hits for the Athletics.
Giants starter Madison Bumgarner went 1 2-3 innings, allowing a run on three hits. He walked two and struck out two.
"I'm not in a routine yet," Bumgarner said. "I'm just trying to get everything to be the way I want it in the regular season. Sure, I want to pitch well but there are things to work on."
Santiago Casilla, credited with the win, and Shane Loux each pitched a scoreless inning for the Giants.
Parker needed just 22 pitches, 18 for strikes, to get through his stint. If not for Marco Scutaro, who battled Parker through a nine-pitch at-bat, he would have been even more efficient.
"Some of those pitches weren't even strikes and he kept fighting them off," Parker said. "He's a tough out every time at bat."
Parker, the No. 2 starter behind Brett Anderson, certainly impressed the A's when he found himself in the starting rotation in the midst of a division race with the Texas Rangers. He and Tommy Milone each won 13 games last year, an Oakland rookie record.
"He's never been a guy who needs to get ramped up," said A's reliever Jerry Blevins, who allowed three runs on four hits while getting two outs. "The more calm and under control he is, the better he pitches."
The Scutaro at-bat notwithstanding, Parker was satisfied with his outing.
"I waited two weeks to throw 22 pitches," he said. "I'm fine with that. I felt my mechanics were good today. I wanted to throw quality strikes and use the least amount of pitches as I could. I wanted to get ahead and I did a good job of that. I begged for it but it's too early for that. Maybe I can argue for an eighth or ninth inning down the road."
He even tried to talk his way out for a third inning, but Oakland manager Bob Melvin would have nothing to do with it.
"He threw the ball really well," Melvin said. "Strikes with everything."
On Thursday, Anderson matched Parker's effort, also throwing two scoreless innings and giving up one hit. Is this a sign of things to come?
"To go out there and do something like that, maybe it will pick up the competitive level among us," Parker said.
Brock Bond hit a two-run homer during the Giants' burst against Blackley. Juan Perez and Gary Brown each drove in two runs.
"That was a lot of runs in not a lot of time," Melvin said.
NOTES: A's RHP Grant Balfour threw 25 pitches off a mound in his first session since undergoing arthroscopic knee surgery at the beginning of camp. ... The Mesa City Council is expected to approve a deal that will bring the A's to Mesa beginning with 2015 spring training and running through the 2034 season, with options that could extend the deal to 2044. The A's lease with Phoenix runs out on Dec. 14, 2014. ... Giants RHP Tim Lincecum will start Saturday's game against the Chicago Cubs in Scottsdale while RHP Boof Bonser makes the start at the Kansas City Royals. ... Milone will make his first start for the A's against the Colorado Rockies on Saturday. ... Giants RHP Sergio Romo served as grand marshal for the Toyota 120 NASCAR Mexico Series race at Phoenix International Raceway. ... The Giants reassigned RHPs Ryan Sadowski and Mason Tobin to their minor league camp. ... A's RHPs Ryan Cook and Sean Doolittle each threw a scoreless inning.