The D-backs broke a 4-4 tie against the Royals' bullpen in the eighth inning. Willie Bloomquist and Justin Upton each singled against right-hander Kelvin Herrera and, after left-hander Collins took over, Miguel Montero belted a two-run double into the left-center gap just past pursuing center fielder Mitch Maier.
"It tipped the very edge of my glove," Maier said. "Obviously it would've been nice to keep it to a sac fly instead of two runs. But I wouldn't change anything, I'd do it again. That was my only chance on the play -- hopefully next time I do that, I'll catch it. . . . I need an extra half-inch on my arm."
Collins got behind Montero, a left-handed hitter, 2-0, when he missed with two curveballs. He came back with a fastball and Montero mashed it.
"It got too much of the plate," Collins said. "I can't say it was the wrong pitch selection, although maybe a little bit with location. But I could've gone changeup and he could've hit the changeup too."
The Royals have lost the first three games of this five-game homestand. A dismal prequel was losing their first 10 games of the season at Kauffman. Their only respite was a 4-3 homestand in which they split four games with New York and took two of three from Boston.
Get them away from home and they're footloose and fancy free. They stand 11-7 in road games.
"You take away the first 10 and it's not that bad," Maier said. "We've got a lot to go, but that 10-game stretch that we lost at the beginning of the year is obviously holding our home record down big-time, but hopefully by the end of the year, it's all in the past."
Luis Mendoza, back in the Royals' rotation for the first time since April 26, was given an early 3-1 lead.
Humberto Quintero doubled home two runs in the second inning that began with singles by Johnny Giavotella and Mike Moustakas. Facing left-hander Joe Saunders in the third, Billy Butler launched a solo home run 414 feet over the center-field wall, his seventh of the season.
Mendoza, after giving up a first-inning run on Montero's RBI double, got into a groove and retired 13 of the next 14 batters with only a walk interrupting the flow.
"He had a tremendous sinker, he did a really nice job of keeping hitters off-balance with it," manager Ned Yost said. "He got through five and had only given up one hit, but just kind of got where he made a couple of pitches that got elevated a little bit and, before you know it -- boom!"
The boom came as Gerardo Parra, Bloomquist and Upton opened the sixth inning with successive singles that accounted for one run. Chris Young knocked in two more with a double down the left-field line.
Saunders took a no-decision in this game, but he has a perfect 4-0 record against the Royals in his career, and is best remembered for stopping Zack Greinke's six-game winning streak at the start of the Royals ace's Cy Young Award year, 2009. Saunders, then pitching for the Angels, won that duel, 1-0, at Anaheim.
This time he wasn't so sharp.
"The first three innings were pretty dicey. I don't know how many pitches I had. It felt like I had 100, felt like I was out there for a long time," Saunders said. "They hurt me. They're a quality lineup. They made me pay for being behind in the count. I just had to settle down and eat up some outs."
He did, lasting until the seventh when sidearming Brad Ziegler, who went to high school in nearby Odessa, Mo., gave up a run on Irving Falu's double and Alex Gordon's single. That tied the score at 4, but the D-backs jumped ahead in the next half-inning.
So it was another loss at home for the Royals.
"The bottom line is we just need to play better," Yost said. "We need to pitch better, we need to hit better at home. We've been really good on the road, we need to find a way to do it at home."