Reliever Craig Stammen is called upon when things go wrong early, but he’s done a great job of keeping the opposition in check and keeping the Nationals in ballgames when they’re down. (Mike Zarrilli/Getty Images)

At the start of every game, middle reliever Craig Stammen treks to the bullpen. The routine is to make sure he’s always available in case that night’s starter doesn’t have his best stuff.

With the Nationals trailing by a run in the fourth inning Sunday, Stammen was summoned from the bullpen just behind the right field wall at Nationals Park. Starter Gio Gonzalez struggled with his command against the Milwaukee Brewers and was pulled after 31 / 3 innings.

Stammen didn’t have any qualms with being inserted into the game so early. It was the second time in his last three relief appearances that he was called upon in the fourth inning.

“There’s a reason I go down there in the first inning,” Stammen said. “You always prepare for the worst and hope for the best. Gio’s been pitching really well, but today his pitch count got up there so I try to back him up as much as I can because he’s helped our team out a bunch.”

Stammen mixed a late-moving two-seam fastball with a slider to retire the eight batters he faced. He recorded two strikeouts on just 29 pitches (20 strikes) in 22 / 3 scoreless innings.

Stammen allowed one inherited runner to score when Jean Segura raced home on a defensive lapse, but by shutting down one of the toughest lineups in the National League, the Nats were able to come away with the 5-4 win.

“We could have sent him up there for more, but we had the lead up by a run with the back of our bullpen guys lined up,” Manager Matt Williams said. “He fills that role really well. He fills a number of roles, but in that situation he can keep us close and in the game to allow us to come back like we did.”

Stammen has logged the most innings of Nats relievers (511 / 3) this season and has the fifth-most innings pitched by a reliever in the major leagues.

Whenever Williams has called upon Stammen for a much-needed salvage job, the right-hander has risen to the occasion.

In a May 17 appearance, he was forced into action in the fourth inning when Gonzalez was tagged for five runs by the New York Mets. Though the Nats couldn’t recover from the early deficit, Stammen tossed four scoreless innings in the 5-2 loss.

In four outings where he has entered in the fourth inning or earlier he has allowed just two runs and struck out 10 in 131 / 3 innings.

Stammen pitched masterfully through July 5 with a 2.68 ERA, but allowed two homers and five runs in Washington’s 8-2 extra-inning loss on July 7 to the Baltimore Orioles. His ERA ballooned to 3.65, but after Sunday’s scoreless outing his ERA stands at 3.51.

“You’re never as good as your first outing and you’re never as bad as your worst outing,” Stammen said. “It’s one of those things where you try to learn from it. Failure is something you can learn the most from. It wasn’t a good night for me but it tested my character and my resolve. Hopefully it helped me have a good outing today.”