"I felt like tonight was as good as my last outing. I just gave up a couple more runs," Oswalt told the Tulsa World newspaper. "When you're through seven innings and thrown around 90 pitches, you know you're commanding your fastball. I felt good tonight. I felt strong."
Oswalt is 2-1 with a 3.50 ERA in 18 innings at Tulsa. He has struck out 14 and given up 14 hits and four walks.
Rockies pitching coach Jim Wright spoke Wednesday with Oswalt and Tulsa pitching coach Darryl Scott, and reported that Oswalt's velocity was not where it soon will be, but the way he adjusted was positive.
"No walks is the big thing, and he kept the ball on the ground with 11 ground-ball outs," Wright said. "He's building up still a little bit. His velocity should hit a little valley, then come back up. But he improvised with pitching.
"He used his sinker and his changeup. I'm not saying he didn't throw hard. He does. But I think he's in that building-up stage, which is good."
Oswalt, 35, is scheduled to throw again Sunday for Tulsa.
According to his contract, Oswalt can opt out June 18 or June 28 if not called up by the Rockies. The Rockies and Oswalt are in close contact, making sure that he's ready when the club decides to place him in the rotation.
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.