The veteran let his catcher guide him through the Nationals' lineup, and then he executed the pitches that were called.
It just wasn't enough.
The Nationals scored four runs in the top of the ninth inning with McCarthy out of the game to cruise past the D-backs, 5-1, in the rubber game at Chase Field.
The loss dropped Arizona to 11 games under the .500 mark. The D-backs are 4-17 at home, a mark that includes two losses to the Dodgers in Australia.
Tied at 1 in the ninth, D-backs reliever Brad Ziegler walked the first batter he faced, Denard Span, and Anthony Rendon followed with a double. Jayson Werth was intentionally walked to load the bases for Ian Desmond, and the shortstop followed with a two-run single to push the Nationals ahead, 3-1.
"I felt good. The arm felt fine," Ziegler said. "I had a lot of swing and misses over the top and a lot of balls chopped foul. I felt like I had decent stuff, but I just didn't execute pitches that well."
Tyler Moore drove home two more runs to cap off the four-run frame for Washington and seal the victory.
"[Ziegler's] been on an incredible run for us, and he didn't have his location today," D-backs manager Kirk Gibson said. "Span put a pretty good at-bat on us. He fought several balls off. After that, [Ziegler] was not able to hit his spot. The Rendon ball was up more than normal and didn't sink as much."
The ninth-inning runs snapped Ziegler's scoreless streak at 19 games and ruined a solid start by McCarthy. It also marked the second time in three games the D-backs were stung late. On Monday, Addison Reed gave up two home runs in the ninth inning in the 6-5 loss to start the series.
"You don't like to lose. It's not how you lose, it's whether you do," Gibson said. "It's disappointing. We had a good game and made some good defensive plays again today. They had a good pitcher and we had a good pitcher, and our guy who has not given it up, gave it up today."
McCarthy and Doug Fister traded zeros for 3 1/2 innings until D-backs second baseman Aaron Hill put his team on the board with a home run in the bottom of the fourth.
Hill shined again, this time on defense, when he saved a run in sixth inning with a diving play to rob Rendon of a base hit. The two-out play stranded Nate McLouth at third base.
The D-backs' lead would not last.
Werth tied the game at 1 with a home run on a 2-0 pitch from McCarthy to lead off the seventh inning. It was the ninth home run allowed by McCarthy this season.
"He was throwing a lot of strikes and getting ahead. His ball was really moving," Werth said. "I got into a 2-0 count, he threw me a cutter. He was trying to throw a strike there, I was ready to hit and I barreled it."
In the end, McCarthy was charged with one run on two hits in eight innings. The veteran retired the first 12 batters in order before giving up a single to Desmond to start the fifth inning. He also struck out seven.
What's more, the outing marked the first time McCarthy allowed two hits or fewer in eight innings in his career, and it came one day after Bronson Arroyo threw a complete game in Arizona's 3-1 win.
Overall, D-backs starters are 6-2 with a 2.70 ERA with seven quality starts in 12 games this month.
"I'm happy that we have been better," McCarthy said. "It was rough the first few weeks where we just felt like the five outcasts and it didn't matter who was starting, it was like we were the guys sitting outside wasting everybody's time. At least now we are contributing again and having some better performances and taking us deeper into games, which is what we were meant to do from the beginning, it just took us a little while to get going."
It's still been quite a turnaround for the D-backs. They started the season with a 5-15 record and finished April with a 9-22 mark. The club has won eight of its last 13 games and three of its last four series.
"The players have been great the whole way. They have never hung their head or given up," D-backs general manager Kevin Towers said. "It all goes with our pitching. The minute our pitching got in line and our bullpen got the rest they needed and the starting pitchers went deeper into games, we are playing more like I think we should."