That all changed in the span of four batters in the fourth inning, as the Rockies rallied for a 9-4 win on a chilly night at Coors Field.
The loss dropped the D-backs to 1-7 on the season, the worst record after eight games in franchise history.
"Nobody likes to lose," D-backs manager Kirk Gibson said. "People get frustrated. But we're professionals. We have a lot of pride. We'll come back and play hard tomorrow."
The D-backs have gone out of their way to emphasize that it is too soon to panic, but catcher Miguel Montero issued a word of caution after the latest loss.
"So far we feel good," Montero said. "Obviously we keep talking about, 'It's early, it's early,' but who cares? We've just got to pick it up right now, because the next thing you know, you're going to be 1-15 and it's going to be hard to pick it up like that. So we either pick it up right now, or things can get ugly."
Saturday held promise early when the D-backs made De La Rosa throw 42 pitches in the first inning as they took a 1-0 lead on an RBI double by Martin Prado.
The D-backs kept the pressure on De La Rosa in the second in making him throw 19 pitches and by scoring a run when Justin Morneau committed an error on a McCarthy grounder, allowing Chris Owings to score from second.
In the third, Mark Trumbo continued his hot start with a two-run homer that put the D-backs up, 4-0.
The homer was the fourth of the year for Trumbo, who has driven in 11 runs this year.
"The command got away from him," Rockies manager Walt Weiss said of De La Rosa. "The pitches started mounting. They put together some tough at bats against him, fouled a lot of pitches off. It was one of those nights where you don't have your best stuff, but you got to find a way, and that's what he did."
Meanwhile, McCarthy cruised through the first three innings, allowing just one hit.
But with one out in the fourth, McCarthy walked Carlos Gonzalez, and Michael Cuddyer followed with a two-run homer to right-center to cut the lead to 4-2.
One out later, Nolan Arenado homered to center to make it 4-3.
"I just kind of lost feel," McCarthy said. "I stopped executing pitches the way I had been. I really don't know what happened. I just sort of lost feel for my sinker and started to really struggle with that command-wise. The first two home runs were just two really bad pitches. I really didn't get the sink I wanted and just didn't put it in the location and got punished. From there, it just wasn't great."
Consistent with the tough start to the season by the D-backs, Arenado's home run -- his first of two on the night -- appeared destined to hit off the top of the wall, but in an attempt to make a leaping catch, A.J. Pollock actually knocked the ball over the wall with his glove.
"My timing was fine; everything was fine," Pollock said. "It's just ... I mean, it's how it's been going, man."
The Rockies scored twice in the fifth, including a run on a rare defensive lapse by the D-backs as they claimed a 5-4 lead. They then tacked on runs in the sixth, seventh and eighth.
McCarthy (0-1) wound up being charged with six runs in six innings of work.
"It's low," McCarthy said of the morale in the clubhouse. "But it's just kind of one of those early tests that we have to figure out quickly. It's not just you want to start winning, but you want to put the positivity back in here. You don't want this to snowball into something where you feel defeated for the season. This is eight games. It's bad, but all it takes it a positive thing to turn it and get something going."
For a few innings Saturday, it appeared that might just happen.