DENVER (AP) -- Matt McBride is so new to the Colorado Rockies that he doesn't even have his nameplate above his locker yet.
Didn't take him long to make a big impact, though.
''Just trying to have a good at-bat and hit the ball hard and try to make something happen,'' McBride said.
With one swing, McBride derailed the Royals' roll, snapping their three-game winning streak. Kansas City saw its lead in the AL Central shrink to one over Detroit.
Danny Duffy (8-11) was cruising along with a 2-1 lead until a two-out error by third baseman Christian Colon in the sixth opened the door for a big inning. McBride lined a fastball from Duffy into the left-field bleachers and then zipped around the bases in exhilaration.
''Just had an adrenaline rush,'' he said.
It was McBride's first homer since Sept. 25, 2012, and third of his career. He was called up from Triple-A Colorado Springs the day before after what's been a tumultuous past two seasons. He missed a big chunk of 2013 after undergoing neck surgery and was out earlier this year with a broken foot.
''Another guy with a great story, who's been through a lot,'' Rockies manager Walt Weiss said.
That was more than enough for De La Rosa (13-8), who allowed five hits and two run against his former team. He also got the Royals to hit into four double plays, tying a franchise record for most by a single pitcher in a game.
Even more, he improved to 9-2 at Coors Field - a place that's haunted many a pitcher, but not the hard-throwing lefty.
''I like to pitch here,'' De La Rosa said. ''It's a challenge for me every time I pitch here.''
Duffy was in command most of the night as he allowed five hits and five runs, one earned, in seven innings. After getting two quick outs in the sixth, Colon fielded a grounder and threw a one-hopper that first baseman Billy Butler couldn't scoop. Wilin Rosario singled and Corey Dickerson drew a walk to set the stage for McBride.
''I wish I could take it back and make the play,'' Colon said.
Another hard-luck loss for Duffy, who's the only AL starter with a losing record and an ERA under three runs.
''I can't lose focus like I did on that one pitch,'' said Duffy, whose team finished 15-5 in interleague play. ''I feel terrible for the mistake I made.''
This was just the second time De La Rosa faced his old team. He spent two seasons with the Royals before being dealt to Colorado in 2008 for cash considerations.
He was cashing in on his changeup to get out of one jam after another.
''His changeup, that's his moneymaker,'' Weiss said. ''It's a great pitch.''
Royals manager Ned Yost seconded that opinion.
''His changeup is a killer,'' said Yost, whose team has won 22 of their last 28 games. ''It's a hard pitch to pick up.''
De La Rosa's only mistake was in the second when he grooved a 91-mph fastball that Alex Gordon hit into the right-field bleachers.
Royals: C Salvador Perez was a late scratch because of tightness in his right knee. He will have a precautionary MRI on Thursday.
Rockies: OF Michael Cuddyer was out another day with a strained left hamstring. He said he's confident he will be back in the lineup Friday.
Royals: After a day off, Kansas City begins a three-game series in Texas. Yordano Ventura (9-9) will start Friday. His nine wins are third-most among rookies this season.
Rockies: The Rockies have their second off day this week on Thursday. They begin a three-game series with Miami on Friday. LHP Franklin Morales (5-6) will get the start after missing his last turn in the rotation for the birth of his daughter.