When pitcher Keyvius Sampson walked into Pat Murphy's office, the manager said he could immediately tell something had changed about the 22-year-old.

Sampson, who began the year with Tucson, had been sent down in April after just four starts. Now back with the Padres, the right-hander has a new hop in his step.

A 10-4 record and 2.26 ERA will do that for some people.

"When he walked in the office the first time, I noticed it," Murphy said. "He just has a different spirit about him, a different confidence."

Sampson is a highly touted prospect in the Padres organization, but had an 8.03 ERA to start the year and wasn't able to make it past four innings in any game of his first Tucson stint. He was promptly sent down to the Double-A San Antonio, where he hadn't exactly lit things up in 2012, either.

"It was kind of depressing, a slap in the face getting demoted," Sampson said. "But I had to take it as it was and go out there and find a way to get back (to Tucson)."

Down in San Antonio, and with a new slider added to his arsenal, Sampson finally looked like the Organizational Pitcher of the Year he was for the Single-A Fort Wayne TinCaps in 2011.

He struck out 110 batters and opponents hit .199 in 103 1/3 innings for San Antonio. Then, in his first start back for the Padres on Saturday, Sampson went six innings and allowed just three hits and one earned run against New Orleans to pick up his first career Triple-A victory.

While Sampson said he still just feels like himself, everyone else has noticed the difference.

"When he first got here he looked a little intimidated," pitching coach Bronswell Patrick said about Sampson back in April.

"He's throwing every pitch with conviction now and he looks like the Sampson of old when he was in Fort Wayne," Patrick added.

As the confidence radiates from Sampson, the more tangible reason for his resurgence is the slider he worked on at San Antonio.

Entering this season, Sampson had been a three-pitch hurler - a fastball, change-up and curve. He started learning the slider in Tucson, though Patrick said it was more of a slurve back then.

Now Sampson said he's comfortable throwing the slider in any count. While it sometimes breaks incorrectly, the extra pitch gives him more flexibility on the mound, especially if another secondary pitch isn't working.

Patrick said he now has three pitches capable of getting major-league batters out.

Sampson will have another chance to show his stuff tonight against Oklahoma City.

But, for a player who hit a low point less than four months ago, Sampson said he's not ready to get complacent.

"Every pitch can be better," he said. "If they couldn't, I probably wouldn't be here."

¡Tus Padres!

Tucson 8, Oklahoma City 6

• Highlight: After falling into an early five-run hole, the Padres (66-59) walked off on a three-run blast to left-center field by Cody Decker to win their sixth straight and clinch the series against the RedHawks. Tucson had just one hit through the first five innings against Oklahoma City starter Bobby Doran on the windy Wednesday night at Kino Stadium. But, RBI singles by Reymond Fuentes and Dan Robertson cut the deficit to one in the seventh. Then, after escaping a bases- loaded jam in the top of the eighth inning thanks to a close call, the stage was set for Decker's walk-off, his 15th home run on the season.

• Big number: 0: Tucson went scoreless in the first inning, breaking a five-game scoring streak in the opening frame that coincided with the Padres' win streak. The team had at least one run in its previous five first innings, including 14 combined over the previous three games. The goose egg looked costly Wednesday, until the late heroics by Decker and company.

• Tonight's starters: RHP Keyvius Sampson (1-1, 5.89 ERA), Tucson, vs. RHP Jake Buchanan (4-3, 3.18 ERA), Oklahoma City