DENVER -- On a night when many fans huddled for warmth at wet and frigid Coors Field, catcher Chris Iannetta demonstrated why he is the Rockies’ security blanket.

Iannetta’s go-ahead, two-run homer in the seventh inning -- off D-backs starter Merrill Kelly and through rain and a wind chill in the upper 30s -- lifted the Rockies to a 6-2 win on Tuesday night, their sixth victory in eight games.

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“It was a tough pitch because it was backing up on me -- I kind of one-handed it,” Iannetta said. “I knew I hit it pretty good. It was a matter of if I hit it too high.”

Manager Bud Black did not originally plan for Iannetta to start, but starting catcher Tony Wolters was scratched with a right hand contusion that he sustained on a foul tip late in Monday’s 11-inning victory. Iannetta stepped in and delivered a swing that broke a 2-2 tie and helped bring the Rockies (26-27) to a game below .500 -- not the start they expected, but not a bad place to be, given they opened the season 3-12.

Ryan McMahon's two-run double in the eighth sealed the Rockies' victory, which didn't have a walk-off finish like their previous three wins, all coming in a four-day span.

Iannetta has a way of doing the right thing at the right time.

Since his May 3 return from a strained lat muscle -- an injury that cost him 16 games -- Iannetta has reached base in all eight of his starts, hit three home runs and batted .323 (10-for-31).

“That was a good swing on a hanging breaking ball, and he’s hit a ball hard the last few times he’s played on a lot of at-bats, so that’s a great, great sign for Chris offensively,” Black said.

The offensive improvement of Wolters, who went from batting .170 in part-time duty last year to .296 in 36 games this season, and the solid backup work of Iannetta, hitting .267, helped Rockies catchers enter Tuesday tied for third in the National League with a .778 OPS. With Iannetta and Wolters as the primary catchers last year, the Rockies tied for 11th at .657.

Iannetta, 36, also ushered starter Antonio Senzatela to only two runs allowed, even though the D-backs reached scoring position in five of the right-hander's six innings (Eduardo Escobar homered off him in the other, the third).

Iannetta said his time on the injured list allowed him to undo some of the changes that he thought would work for him.

“It was breaking some of the habits that developed during the offseason,” Iannetta said. “I really tried working on going the other way, but it was just too much muscle tension. It took me a really long time to get out of that, probably until Opening Day and even then, I was still battling it. When I got hurt, it gave more more time to work on it.

“I also switched my contacts. They gave me a lesser power this year because they said I saw better, like in the tests. But over time, my eyes would fatigue and things would get blurry. I battled that all through spring. After I got off the [IL], I had a three-month supply of last year’s prescription, and I went back to it. I’ve been seeing a lot better. That’s been a big thing that’s relaxed me behind the plate and offensively.”