SCOTTSDALE, Ariz. -- A pain-free left shoulder is a welcome stranger who is fast becoming a friend to Rockies relief pitcher Mike Dunn.

“I’d throw a bullpen and look at my shoulder like, ‘Wow, no pain,’” said Dunn, who underwent surgery to clean up his right A/C joint last September, after having pitched in pain during the first two years of a three-year, $19 million contract with the Rockies.

Dunn is not only pain free but effective this spring. His one-inning, two-strikeout fifth inning against the Cubs on Thursday -- Ben Zobrist went down looking, Kyle Schwarber swinging -- was his third scoreless inning this spring.

Before fanning Schwarber left-on-left to end the inning, Dunn got Zobrist and coaxed a fly ball from Kris Bryant, right-handed hitters both. Part of the reason the Rockies signed him was his ability to handle hitters from either side.

Last year, Dunn managed just 25 appearances with a 9.00 ERA. But if Dunn’s health holds, the Rockies hope he approaches the effectiveness he demonstrated in 2017 (5-1, 4.47 ERA in 68 games), or with the Marlins in 2016 (6-1, 3.40 in 51 games).

Being healthy means Dunn, who turns 34 on May 23, can continue transitioning his strategy.

Breaking in with the Yankees (2009), Braves (2010) and early in his time with the Marlins (2011-16), Dunn’s fastball averaged in the 95-mph range, and he threw it more than 60 percent of the time, sometimes considerably more. But in 2016, his final year with the Marlins, he dropped the fastball frequency to 61.6 percent and increased his slider usage. Now the slider and curve will continue to increase in importance, even though he’ll throw the fastball about half the time.

“That’s a pat on the back to Mike,” Rockies manager Bud Black said. “The curveball is going to come into play more, the slider, the two-seam fastball that has sink to it. He’s going to pitch a little bit more than maybe Mike Dunn in Miami.”

Dunn will test his health in the coming days. After a slightly slower schedule than other relievers, he’ll throw Sunday, then Wednesday, Friday, and a back-to-back March 17-18 before tapering off for the regular season.

Dunn is excited to be a full participant once the regular year begins.

“It’s going to be a long year, but it’s going to be a fun year for me,” Dunn said. “I pitched in 25 games last year, the least amount I ever had in my career. I had to take a step back and appreciate the game, being away from it as long as I was. I’m very excited.”