Happ (1-0) struck out six batters over seven innings and combined with Fernando Abad as Triple-A Oklahoma City one-hit Iowa, 4-0, on Sunday.
"I felt pretty good. I was attacking the zone and, for the most part, I was around the zone. That helped get some early outs and kept my pitch count manageable," said Happ, who was optioned to Oklahoma City by the Astros on Aug. 6.
"I was throwing my fastball, a cutter, a curve and a change. I was using my change-up to get more outs early in the game and then the curve as the game went on."
The only hit the 28-year-old allowed was to the second batter he faced, Lou Montanez, who laced a one-out double to right field in the first inning. Happ, who threw 59 of his 94 pitches for strikes, retired the next two batters to strand Montanez at second base, and that was as far as any Cubs hitter advanced all day.
He used an around-the-horn double play to erase a one-out walk in the second, and he set down the next 10 batters until issuing a free pass to Marwin Gonzalez in the sixth. Welington Castillo drew a base on balls in the seventh to give the I-Cubs their fourth baserunner of the afternoon, but DJ LeMahieu grounded out and Matthew Spencer struck out to complete Happ's third Pacific Coast League start.
"I wanted to be aggressive," the 6-foot-6 Illinois native said. "There have been a few games where the pitch count has caught up with me, so I wanted to get ahead of hitters. I was hoping to come back out [for the eighth], but they had a plan and it worked out. Fernando Abad did a good job."
Southpaw Happ yielded four runs -- three earned -- on six hits and three walks over five innings in a 5-4 win against Reno on Tuesday, and he saw Sunday's performance as another positive step toward a return to Houston.
"I don't see a whole lot standing in my way," the Northwestern University product said. "It is all about being confident. I just want to tighten everything up and throw everything for strikes. This game is a game of inches. Hopefully, I will be back up there soon."
Happ owned a 12-4 record with a 2.93 ERA in 35 appearances -- including 23 starts -- with the Phillies. Since then, however, he has been unable to replicate his success.
A left arm injury cost him half of 2010, and he made just three starts for Philadelphia before being traded to Houston last July in the deadline deal that sent Roy Oswalt to the Phillies.
This year, Happ posted a 4-14 record and a 6.26 ERA in 22 outings before being sent down to the Pacific Coast League earlier this month. In his three starts for the RedHawks, Happ is 1-0 with a 1.50 ERA and 16 strikeouts and nine walks over 18 innings. He acknowledges that he's not the same pitcher he was in '09, but he's determined to contribute in the Majors again.
"I would like to say [I'm the same], but the fact of the matter is that I've not been as consistent as I was two years ago," he said. "That is where I want to get back to. When I'm consistent, good things happen.
"Hopefully, I can have more outings the same. I felt good and I want to continue to work and refine things. It's about consistency. That's the goal."
Abad pitched two perfect innings of relief en route to the fourth RedHawks shutout of the season and the first since Andy Van Hekken and Wesley Wright blanked Memphis in a 7-0 victory on July 24.