After a sparkling season debut against the slugging Atlanta Braves, Nationals right-hander Austin Voth struggled against the slumping Kansas City Royals and Detroit Tigers. (Patrick Semansky/AP)

Two days before the all-star break, the Washington Nationals sent their fifth starter, Austin Voth, to Class AA Harrisburg. They needed a spot on the roster to activate ace Max Scherzer off the paternity list for Saturday’s game, and moving Voth made sense because he had made his last start of the season’s first half the night before.

After an impressive season debut late last month, Voth struggled in his next two outings. The team’s fifth starter spot, which has been shaky all season, stayed that way. So the transaction prompted a question: Will Voth come back?

“It’s definitely something that we’re talking about,” Manager Dave Martinez said Saturday. “He’s not going to pitch for a while, so we want him to go down and get his work in, make sure he’s ready.”

The Nationals’ second half starts Friday in Philadelphia, and Martinez intimated he expects Voth to rejoin the team. The manager said the right-hander will pitch Wednesday for Harrisburg to keep him on schedule throwing every fifth day, “so that will put him back some time [around the second series].”

The Nationals have a scheduled day off Monday, so they could go without a fifth starter until July 22. Still, the question of who the fifth starter will be for the long term remains pressing because, for all the strides the Nationals made to end the first half 47-42 and atop the National League wild-card standings after a 19-31 start, the spot seems as far from settled as ever.

At first blush, this might look like no problem at all. The Nationals have one of the best and highest-paid rotations in baseball, with Scherzer (2.39 ERA in 129 1/3 innings), Stephen Strasburg (3.64 in 116 1/3), Patrick Corbin (3.34 in 113 1/3) and Aníbal Sánchez (3.66 in 83 2/3). Martinez acknowledged that he is blessed to have four dependable starters.

Yet the instability beyond the top four has been costly. Since May 27, the Nationals have won 25 games and lost 10, and five of the defeats were started by the fifth spot in the rotation. To continue winning, to push for the playoffs as aggressively as they seem poised to, the Nationals need stability to lead to improvement. Continuing to ride the hot hand in the fifth starter spot doesn’t allow the pitcher or the team behind him to find the consistency that players covet.

After his past two starts, it’s fair to wonder whether Voth’s first outing — six innings, two runs, no walks and seven strikeouts against the first-place Atlanta Braves — was an aberration. He lacked the same crispness in his two subsequent starts, and his fastball velocity, which shot up to touch 96 mph against the Braves, dipped back to the normal low 90s. His command faltered, too.

In 4 1/3 innings against the Detroit Tigers, baseball’s worst offense tagged Voth for six hits and three runs. In 4 1/3 innings against the Kansas City Royals, baseball’s sixth-worst offense tagged him for five hits and four runs. Both times, the 27-year-old described his struggles as a byproduct of feeling “a tick off,” especially when trying to locate glove-side fastballs.

“Last two games, I just haven’t been able to [throw them for strikes],” he said Friday after facing the Royals. “That’s something I got to come in tomorrow and look at video to see if that’s something that’s kind of causing me to lose command.”

The rotation fluctuation seems urgent because, if the Nationals decide Voth is not the long-term solution, they might be back to square one. The original candidate for the spot, right-hander Jeremy Hellickson, hasn’t pitched since May and appears to be out of the mix because the Nationals moved him to the 60-day injured list last week with right shoulder stiffness.

The right-hander who replaced Hellickson, Erick Fedde, looked strong in his first four starts, compiling 20 innings and a 2.70 ERA, but then command problems derailed him. Fedde allowed seven runs in 9 2/3 innings over his past two starts while throwing just 56 percent of his pitches for strikes. The Nationals optioned him in late June to Class AAA Fresno, where he has thrown 10 innings in two starts and allowed 19 hits and 14 runs.

Another potential successor, right-hander Kyle McGowin, auditioned in late May and allowed five runs in four innings to baseball’s second-worst offense, the Miami Marlins. He has not started in the majors since, though he has started twice in Fresno and allowed three runs over 13 innings.

Even when Voth’s chance arrived, his season debut earned a restrained endorsement from Martinez. The manager praised Voth’s poise, “aggressiveness” and use of all four quadrants of the plate, but all he said was that his first start “warranted another start for him here.”

Looking back on the two outings since, Voth has managed to navigate around some of his mistakes even as his pitch count climbed. He hasn’t been efficient, but Martinez also thought he competed without his best stuff and without becoming truly erratic. To him, that meant something.

Martinez understands the Nationals’ need to solidify the fifth starter role, and he said “it’d be great” to do so soon. Without a roster move, it appears what Martinez said in Detroit, after Voth’s first worrisome start, will hold true as the second half starts Friday.

“He’s our fifth starter, and he’s here,” Martinez said then. “We’re going to try to get him going and keep him going.”

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