Kelly struck out seven and allowed two runs on five hits over six innings Tuesday but did not figure in the decision as the San Antonio Missions edged the Tulsa Drillers, 3-2.
Despite a 3.31 ERA, Kelly has yet to earn a win in three Texas League starts. Against the Rockies' Double-A affiliate, he surrendered solo homers to Tim Wheeler and Ben Paulsen in the third inning but was solid the rest of the way.
"Me and [catcher] Ali [Solis] were on the same page," Kelly said. "Early on, it was a lot of fastballs. I was just trying to get ahead of the count. The defense made a lot of great plays. Ali was great back there, I felt I could make any pitch and he would stick it for me."
Kelly, selected 30th overall by the Red Sox in the 2008 Draft, struggled with consistency last season with Double-A Portland, where he went 3-5 with a 5.31 ERA in 21 starts. He struck out 81 batters over 95 innings but was shut down on Aug. 18 after straining a muscle in his back. It was a new experience for Kelly, who had never spent an entire season solely as a pitcher.
"Throwing every fifth day is a lot different," he said. "Being in the Eastern League with a lot of great prospects, I had a lot of up and downs, had some good outings and some bad outings. I learned a lot from last year and I think it made me a better player."
Kelly, MLB.com's No. 22 prospect, was acquired last December with first baseman Anthony Rizzo and outfielder Reymond Fuentes when the Padres shipped All-Star first baseman Adrian Gonzalez to the Red Sox. After struggling in his Missions' debut on April 8, Kelly has allowed two runs in each of his last two appearances and has held Texas League hitters to a .213 average over 16 1/3 innings.
"It was kind of a weird moment," Kelly said of learning about the trade. "I didn't know what to think or how to act. I have the utmost respect for the Red Sox, but from the other side I'm really excited to be with the Padres. They definitely have great pitching coming up through the organization. I'm excited to be here and learn as much as possible."
The key going forward, he added, is being able to maintain his focus between starts and carry that out to the mound.
"I just need to be consistent," Kelly said. "That's what this game is about -- being the same pitcher every day and get better on the four days before the start and go out there on the fifth day and compete."
Former first-rounder Christian Friedrich nearly matched Kelly, yielding two runs on five hits while fanning five over five frames. MLB.com's No. 50 prospect rebounded from a rocky outing on April 14, when he surrendered seven runs over six innings against Corpus Christi.
Solis slugged a solo homer, his second, and rehabbing outfielder Kyle Blanks was 2-for-4 with a run scored for San Antonio. Kyle Phillips drove in the go-ahead run with a sacrifice fly in the eighth.
Brad Brach, who was named 2010 California League Pitcher of the Year after finishing third in the Minors with 41 saves, pitched a perfect ninth for his third of the season.