A relative strength all season, the Nationals bullpen fell apart on Saturday night against the San Francisco Giants.

Tyler Clippard was charged with four runs in the seventh inning alone and Washington relief pitchers allowed six runs overall in a disappointing 10-5 loss to the Giants at Nationals Park.

The Nats held a 5-3 lead heading into the sixth inning. Ryan Zimmerman, Michael Morse, Ivan Rodriguez and pitcher Craig Stammen all drove home runs. But Clippard gave up a solo homer in the seventh to Aaron Rowand, walked the next two batters and then allowed an RBI single to rookie Buster Posey. Doug Slaten came on in relief and immediately gave up a two-run double to Juan Uribe. Posey added a two-run homer in the ninth off Nats reliever Miguel Batista.

There wasn’t much Clippard could say after that kind of outing. So he didn’t, leaving the ballpark without speaking to reporters. The reasons for his frustration are evident. Clippard has allowed 11 earned runs in his last 5 2/3 innings. During that stretch his ERA has risen from 1.58 to 3.31.

But pinpointing a specific reason why is difficult.

“Looks to me like he might be overthrowing a bit,” said Nats pitching coach Steve McCatty. “Sometimes when you’re struggling there’s a tendency to go harder – and that’s not what you want to do.”

McCatty has looked at video of Clippard’s recent performances and noticed nothing drastically different. Clippard’s command isn’t a strength anyway so falling behind in the count isn’t unusual. He’s always used his offspeed pitches, especially the change-up, to counter that fault.

But the Nats can’t afford to lose Clippard. He was dominant the first six weeks of the season, had a rough patch in mid-May, and quickly righted himself. But he hasn’t been himself since blowing a save against Baltimore on June 25. Clippard has allowed at least one run in five of his last seven games and is now more of a co-setup man. That’s in part because of his own struggles and in part because rookie Drew Storen (2-1, 2.16 ERA) has established himself as a reliable presence since a May 17 call-up from Triple-A Syracuse.

“Sometimes a few days off he may come back just like he was,” said Washington manager Jim Riggleman, who may give Clippard a day off on Sunday, the final game before the All-Star break, after he threw 33 pitches on Saturday. “For now I’ll try and keep him in that [role] if there’s a couple outs in the sixth or if we get to the seventh get him the ball and see if we can get him going again.”

To blame the loss entirely on Clippard is unfair, of course. The Nats scored five runs in the first four innings and knocked San Francisco starter Jonathan Sanchez out of the game. But they couldn’t build on it. Rodriguez grounded out to third base with the bases loaded and two down in the fifth inning. In the sixth a double, a stolen base and a walk led to nothing when Ian Desmond’s poor bunt got Morse thrown out at third. Desmond then erased himself when he was caught trying to steal second. Washington never put another runner on base. The Nats again dropped back to 10 games under .500 at 39-49 and are 6-5 over their last 11 games. The Giants improved to 46-41. The two teams have split the first two games of the series.

“We had an offensive night it looked like – we scored five runs,” Riggleman said. “But there was some more out there that we didn’t get. And that came back to bite us.”