He finished with 56 pitches -- 38 for strikes. In addition to the five earned runs he was tagged with, Oswalt struck out four and walked one through four innings.
But Oswalt said after the game that his numbers on the night were just that -- numbers.
"I felt strong. That's the best thing about tonight," Oswalt said.
After walking the first batter of the game on five pitches, Oswalt settled down, getting the second batter to ground into a double play and retiring the next four he faced through two innings.
Things unraveled quickly in the third as the No. 7 hitter Anthony Seratelli in the Omaha lineup grounded the first pitch of the inning down the first-base line for a leadoff double.
Oswalt forced the next batter to fly out to right and then allowed base hits to the next three batters base. That scored a run and loaded the bases with one out.
Omaha center fielder Wil Myers followed by launching a 2-0 fastball into the left-field seats for a grand slam and gave Omaha a 5-1 lead on the way to a 7-2 win.
The 34-year-old right-hander said the pitching approach in the Minors is different than that at the Major League level.
Oswalt said pitching in the big leagues is about winning while pitching in the Minors is about getting in work and preparing for the next level.
"It's funny. When you throw in the Minor Leagues, they don't let you throw a lot of pitches," Oswalt said. "They swing early, and you don't get to work on a lot of stuff.
"Tonight I think out of six hits, I gave up five on first-pitch fastballs. So you try and get your fastball established and try to work on it as much as possible. But when they swing at first pitches, it's hard to work on your other pitches," he added.
Oswalt's start against Omaha followed his Triple-A debut Saturday in which he pitched two scoreless innings against Albuquerque as the starter, giving up three hits and a walk while striking out one.
Oswalt, who spent 11 years in the Majors with Houston and Philadelphia, has said he wants to take a spot in the Texas rotation after four Minor League starts.
He was signed last week when Neftali Feliz went on the disabled list with a sprained right elbow.
Feliz is not expected back until the All-Star break or later.
Scott Feldman, who replaced Feliz in the rotation, has struggled since taking over the spot.
Feldman was roughed up for eight runs in 1 2/3 innings in a 12-1 loss at Oakland Monday night.
Making matters even more dire for the Rangers came news Thursday that Derek Holland was going on the 15-day disabled list with shoulder fatigue.
There had been rumors this week that the Rangers would be interested in accelerating Oswalt to the Texas rotation given the situation in Arlington.
But Oswalt said he has not been asked to change his approach or push any harder to make it back to the big club more quickly.
"We just kind of had a plan," Oswalt said, "and I'm trying to push them more than they're pushing me, for sure."
"Just the way I felt tonight, I felt I could go out for another two or three innings and pitch into the seventh inning," Oswalt added.
Feldman (0-4) is scheduled to pitch Saturday at San Francisco while Alexi Ogando (1-0) is expected to come out of the bullpen Sunday and start against the Giants.
Oswalt was 9-10 with a 3.69 ERA last season with Philadelphia that included two stints on the DL.