Catcher Wilson Ramos of the Washington Nationals looks on as Garrett Jones of the Pittsburgh Pirates hits a 2-RBI double. (Rob Carr/Getty Images)

In front of Ian Desmond and Roger Bernadina’s locker, Washington Nationals Manager Davey Johnson motioned swinging a bat. Johnson hoped to pass along a few batting techniques after his players on Sunday finished another game packed with stranded base runners and — more damaging and more rare — disastrous starting pitching.

In a 10-2 loss against the Pittsburgh Pirates, the Nationals — known for keeping games in the low digits with solid pitching and defense and just enough timely hitting — dug a deep hole midway through the second inning, by which point they trailed by eight runs and had sent five batters to the plate.

Washington fell below .500 with a loss at Nationals Park, where they left 10 runners stranded. Under Johnson, the Nationals are 2-5 with two of the last four losses coming by six or more runs. Since June’s eight-game winning streak, the Nationals have dropped seven of their last 14 games.

“I thought this was a good game, but then we get way behind and then we start swinging the bats,” Johnson said. “We got nine hits. It’s just one of those things. We have to stay optimistic.”

Against starter Jason Marquis, Pittsburgh scored three runs in the first inning and batted through the order in the second to add another five runs on its way to building an 8-0 lead.

Jayson Werth of the Washington Nationals holds his wrist after getting hit by a pitch during the sixth inning. (Rob Carr/Getty Images)

The Nationals missed a prime opportunity to force a scoreless first inning when Chase d’Arnaud hit a soft chopper back to Marquis, whose throw to second base for a potential double play was scored an error. As the ball traveled to the edge of the infield, Alex Presley advanced to third. After Garett Jones flied out, Presley scored on Andrew McCutchen’s RBI single. With Neil Walker batting, d’Arnaud stole third and beat Wilson Ramos’s throw to third. Walker followed with a singled to left field to score d’Arnaud. By the time Lyle Overbay’s single traveled to right center field, McCutchen crossed home plate and the Pirates led 3-0.

“We’ve done a great job defensively all year and we’re out there battling trying to make plays and sometimes it just doesn’t happen,” Marquis said. “As a pitcher you still have to battle and get guys out, and I wasn’t able to do that.”

Jones’s two-RBI double to center continued the Pirates’ offensive onslaught in the top of the second inning. McCutchen followed with a one-out, RBI double to center field to increase the Pirates lead to 6-0.

Marquis’s rough start Sunday gave him two consecutive uneven performances. Tuesday in Anaheim, Marquis allowed three earned runs on four walks and eight hits in five innings. He entered that start with a 3.53 ERA. After Sunday, it had ballooned to 4.11 after 42 pitches and six earned runs on eight hits.

“I lost too many balls in the zone,” said Marquis, who is 7-3 this season. “I didn’t have the late action on my ball. It was just one of those days. Obviously, I’m not happy about it. But it’s just one start in a long season. Turn the page and be ready to go next time out. . . . Sometimes you get on the mound and it doesn’t go your way. Obviously that cost us the game.”

Collin Balester, who had his longest outing since he became a reliever last April, entered the game to relieve Marquis and gave up two more runs before forcing a groundout and striking out Michael McKenry to end the top of the inning. He threw 76 pitches in four innings, allowing two earned runs on four hits and two walks while striking out five.

“That’s going to win us games next week,” closer Drew Storen said. “No doubt about it.”

Catcher Wilson Ramos of the Washington Nationals has water poured on his head between innings. (Rob Carr/GETTY IMAGES)

Ramos was one of the few Nationals to show signs of offensive life. The catcher’s two-run home run landed just over the left-center field wall to cut the Pirates’ lead to 8-2 in the bottom of the second.

“We have been trying to play over .500 every time,” Ramos said. “We’ve got to keep playing.”

Pittsburgh beaned two of the Nationals regulars to force them out of the lineup by the end of the four-game series. Michael Morse was scratched from the lineup with a baseball-sized bruise on his forearm from Saturday’s game. Jayson Werth, meanwhile, continued to struggle at the plate, recording a strikeout and a pop fly before leaving the game in the sixth inning. Morse left the Nationals’ clubhouse wearing a white padded sleeve over his left arm. Werth will be out of the lineup “for a day or two,” according to Johnson after Pittsburgh starter Kevin Correia nailed him in the left arm with a 93-mph cutter.

“We kind of start getting healthy and then bang, something else happens,” Johnson said. “That’s just baseball. The bench has got to pick you up.”