DENVER -- This was not the way the D-backs envisioned ending their series with the Rockies. Nor was it the way they wanted to begin a nine-game sojourn through the National League West.

Yet the D-backs stand 0-3 on the trip after watching the Rockies beat up their ace, Dan Haren, en route to an 8-2 win Thursday afternoon at Coors Field.

"It's wonderful to sweep for the first time this year," Rockies manager Jim Tracy said. "The manner in which we did it, and the entire series, is really what we were all about when we became the team we became last year."

Coming off a 4-1 homestand against the Giants and Blue Jays, the D-backs thought they were on a roll.

"That's the last thing I was expecting was going to happen," outfielder Chris Young said of the sweep.

The D-backs travel to San Francisco for a three-game weekend series before wrapping up the trip against the Dodgers in Los Angeles.

"It was a really good homestand and to start the [trip the] way we did it's definitely deflating," catcher Chris Snyder said. "But there's still six games left on this trip, there's still a lot of baseball to play."

D-backs manager A.J. Hinch didn't want to pin the entire blame on Haren, but his continued struggles no doubt must concern the team. Haren, who gave up eight runs in 6 1/3 innings, is now 5-4 with a 5.35 ERA and has allowed 16 home runs already this season, including four in each of his last two starts. He gave up 27 all of last year and just 19 in 2008.

"I'm struggling, obviously pretty bad," Haren said. "Obviously I've had a lot of trouble keeping the ball in the yard. It's obviously frustrating. It's tough to deal with. I've never dealt with anything like this in my career. Hopefully I'll come out of all this a better pitcher."

The D-backs can only hope that is the case, but first they have to figure out what exactly is causing Haren's problems.

"It all boils down to execution of pitches," Hinch said. "He's battling, he's trying and right now every mistake, every bad pitch he's making is getting punished. He's trying. It's really hard to describe because it's nothing that anyone is ever expecting when he's on the mound. He's as good as it gets when he's on and he's just had a hard time finding that consistency this year."

The Rockies didn't let Haren get into the rhythm of the game before jumping all over him.

Two batters in the Rockies were up 1-0, and then after Haren struck out Jason Giambi, he left a cutter out over the plate and Troy Tulowitzki hit a two-run homer to give the Rockies a 3-0 lead.

"I didn't have a cutter," Haren said of what is normally his best pitch. "I threw four cutters the whole game and I usually throw 30 or 40. It just wasn't working for me today."

Yet somehow Haren found a combination of his fastball, curveball and split-finger that allowed him to retire 14 batters in a row heading into the sixth.

Haren allowed one run in the sixth, but the game was still manageable at that point with the Rockies clinging to a 4-2 lead.

Things, though, would get out of hand in a hurry in the seventh.

After getting Ian Stewart to fly out to start the frame, Haren allowed a single to Clint Barmes and a homer to pinch-hitter Seth Smith.

Carlos Gonzalez followed with a homer and so did Ryan Spilborghs and suddenly the Rockies had an 8-2 lead with Haren headed for the showers.

It was the first time in his career that Haren had allowed back-to-back-to-back homers and it was the first time in 84 starts that he had given up as many as eight runs in a game.

"It's not being tired," Haren said. "It's just a matter of making pitches. A couple of balls just caught too much plate and good hitters are going to make you pay. I made some bad pitches and paid for it."

Hinch was asked if he considered taking Haren out during the home run barrage, which took place in a five-pitch stretch.

"He's our horse, and it's hard to take him out of the game even when he's leaving pitches up," Hinch said "It happened quickly."