"It usually takes me a few [games] to get going," Kelley said Wednesday. "I stay away from the slider my first few outings just to get the arm strength built up. When you're in Arizona and you are just throwing fastballs, late in a Spring Training game, balls get hit."
They haven't much of late when Kelley has been on the mound, as he's allowed one hit in his last 5 1/3 innings, with one walk and six strikeouts.
"I feel good," Kelley said. "I think I'm ready to go."
That's a good sign for the Padres, who will likely use Kelley a lot in the eighth inning to help set up closer Joaquin Benoit.
The Padres traded Minor League pitcher Johnny Barbato to the Yankees for Kelley, who is making $2,835,000 this season and will be a free agent following the season. General manager A.J. Preller picked up two power arms for the back end of the bullpen in the span of a week after Christmas, adding Kelley and Brandon Maurer from the Mariners.
The Padres liked Kelley's fastball-slider mix and felt he could miss bats late in the game, providing a nice piece to help get the ball and the lead to Benoit.
"This guy can make pitches. He can truly pitch to a hitter's weakness," said Padres manager Bud Black.
The slider has been a true weapon for Kelley, who had the eighth-best strikeout rate on the pitch in the game a year ago. According to FanGraphs, only Al Alburquerque of the Tigers threw his slider more (63.7 percent) more than Kelley (57.7) did among relievers in 2014.
Kelley can't say for sure if he'll use the slider as often, but he'd like to use the fastball more -- and inside to right-handed hitters, which has been a point of emphasis in Spring Training.
"I'd like to throw inside a little more to right-handed batters and that's something I've worked on this spring, so I'm trying to get comfortable with that," Kelley said. "I think it will help open the outside a little more to keep guys from leaning out [over the plate]."