What a difference nearly two months makes.
De La Rosa pitched seven strong innings in his fifth straight win and drove in two runs, helping the Rockies beat the Arizona Diamondbacks 10-6.
"We're being chased now," said Rockies manager Jim Tracy, who took over when Clint Hurdle was fired after an 18-28 start.
After Tracy took over, the Rockies slipped to 20-32 before going on an 11-game winning streak. They are now nine-games over .500 (51-42), and have taken a half-game lead on San Francisco, who lost to Atlanta, for the wild card.
"With the guys we had coming out of spring training, we could have been doing this from the very beginning," second baseman Clint Barmes said. "It's just nice that it came around. I definitely think we have something special here."
The team's revival has paralleled De La Rosa's resurgence. The left-hander started the season 0-6 but has gone 7-1 since. On Monday, he gave up one run on four hits, struck out six and walked one. He had a career-high two hits. The two RBIs were also a career best.
"I think my control is much better and I have much better command of my fastball," said De La Rosa (7-7).
He kept the Diamondbacks in check while the Rockies offense jumped on Arizona starter Doug Davis.
In the first, Barmes singled, stole second and moved to third when Brad Hawpe reached on a fielder's choice. With two outs, Troy Tulowitzki doubled into the gap in right-center field to score both runners and make it 2-0.
They padded their lead in the second. Ian Stewart led off with a double, Iannetta singled with one out and De La Rosa's safety squeeze scored Stewart from third. Fowler followed with his fourth home run of the year to make it 5-0.
Colorado chased Davis in the third. With one out, Davis loaded the bases with three walks and Seth Smith hit a two-run single to center to give the Rockies a 7-0 lead.
De La Rosa greeted reliever Blaine Boyer with an RBI single to left to make it 8-0 after three innings.
"It's about time," De La Rosa said. "My first real hit of the year."
Davis (4-10) gave up eight runs on six hits, struck out one and walked four in 2 1/3 innings. It was Davis' shortest outing of the season.
"It wasn't fun," Davis said. "I can put it that way."
Every Colorado starter except Hawpe had at least one hit, and the Rockies scored at least one run in each of the first five innings.
"We dug ourselves such a deep hole that it was difficult to get out of," Arizona manager A.J. Hinch said. "They were in control most of the game."
Iannetta made it 10-1 in the fifth with his 11th home run.
"I really feel what we did through the first seven innings was one of the more complete games that we've played," Tracy said. "We really did a tremendous job up and down the lineup."
It wasn't enough to keep the Rockies from moving into the NL wild card lead.
"It's still really early in the second half, but one thing you can bear in mind, as of right now you know you don't have to look around and talk about, 'Well, we need help here.' That's a nice situation to put yourself in," Tracy said.
Rockies OF Ryan Spilborghs was excused from the team because his wife went into labor Monday morning. ... Helton needs one double to become the 50th player in major league history to hit 500 doubles. ... The Diamondbacks recalled INF Ryan Roberts from Triple-A Reno. Roberts played second Monday night.