McCarthy takes the mound Friday night when Arizona seeks its fourth victory in five tries against the visiting San Diego Padres and both teams look to avoid a third straight loss.
The Diamondbacks (26-21) have scored two runs or fewer seven times while going 5-6 over the last 11 games, including Wednesday's 4-1 loss to Colorado. They went 3-3 on their road trip, scoring 12 runs over the last five.
"We had three games we scored some runs and the other three we didn't at all," manager Kirk Gibson said. "It seemed like a longer road trip than it was.
"I felt we didn't have as much energy as we've had in the past. It's going to happen. Time for an off day."
Arizona's starters, though, posted a 2.25 ERA during the trip and have a 2.37 ERA over their last 14. The team's 3.32 ERA ranks among the best in the majors, and McCarthy (1-3, 4.74 ERA) has helped improve that mark lately.
He picked up his first win as a member of the Diamondbacks on Saturday, pitching a three-hitter in a 1-0 victory over Miami. It was his second straight solid outing after pitching eight scoreless innings in a 4-2, 10-inning loss to Philadelphia on May 12.
"It's nice to know that that's something that I can start looking toward, that I can get deeper into games," said McCarthy, who had a 6.75 ERA through his first seven starts.
"The win part, I don't care. It's a win for us, which is the only thing I care about. My numbers and stats are really inconsequential."
The right-hander has never faced the Padres (21-25), who have averaged 5.9 runs while winning eight of 10 meetings in Arizona.
San Diego lost the final two of a three-game series with St. Louis, falling 5-3 on Wednesday. Jedd Gyorko hit a 438-foot solo homer and is batting .433 over his last eight games.
The rookie infielder went 6 for 12 with a two-run homer as San Diego took two of three from the visiting Diamondbacks from May 3-5. Chase Headley had a hit in each game of that series as part of a 13-game hitting streak, but he's hit .205 in 12 contests since that run ended May 10.
The offense hopes to provide some support for Eric Stults (4-3, 4.05), who looks to continue his hot stretch.
Stults is 2-1 with a 2.29 ERA over his last three outings after giving up one run and four hits in eight innings of a 2-1 win over Washington on Saturday.
He hadn't pitched that deep into a game since tossing a four-hitter to beat San Francisco 8-0 while with the Los Angeles Dodgers on May 9, 2009.
"I'm not the guy who threw 93 miles per hour like I used to be, but the hitters in this league are good," Stults told the team's official website. "I used to be pretty predictable, throwing a fastball and changeup. When you have four pitches, you can do a lot more."
The left-hander has been solid in five starts versus Arizona, going 3-2 with a 2.67 ERA.