The A's No. 3 prospect struck out eight over six one-hit innings, but Triple-A Sacramento was blanked, 2-0, by the Reno Aces in its home opener Friday night at Raley Field.
"This is not going to happen much," Peacock said. "Not with this lineup."
The 24-year-old right-hander allowed one run on two walks, a wild pitch, an error and Konrad Schmidt's sacrifice fly in the second. Employing the advice of pitching coach Scott Emerson -- "Work ahead, throw strike one" -- he righted himself quickly, striking out the side in the third, pitching around Cody Ransom's single in the fourth and retiring his final eight batters. He threw 62 of 101 pitches for strikes.
"I feel like I did really good; I guess I just lost it there in the second," said Peacock, who utilizes a fastball-curveball-changeup repertoire. "Everything was working tonight."
Peacock (1-1), MLB.com's No. 75 overall prospect, gave up four runs -- two earned -- on five hits over six innings in his organizational debut last weekend.
The A's acquired him with catcher Derek Norris and two other players in the offseason deal that sent left-hander starter Gio Gonzalez to the Nationals. Norris caught all nine innings and is batting .333 in eight Triple-A games, despite an 0-for-4 effort Friday.
A 2006 41st-round Draft pick, Peacock went 15-3 with a 2.39 ERA in 25 outings, including nine at Triple-A Syracuse, last season. He was named Eastern League Pitcher of the Year and earned a MiLBY as Double-A Starting Pitcher of the Year.
Aces starter Zach Kroenke (1-1) held the River Cats in check for six innings, giving up three hits and issuing three walks while striking out five.
Reno tacked on a run in the ninth, when D-backs No. 18 prospect Ryan Wheeler tripled home Ransom against reliever Merkin Valdez.
Sacramento center fielder Grant Green, the A's No. 6 prospect, went 3-for-4, two nights after driving in six runs. He came up with two outs and two on in the bottom of the ninth but grounded against Bryan Woodall, who notched his first save.
"Grant has a good approach at the plate," Peacock said. "I thought we were going to get it, but it happens."