Tanner Roark allowed two runs on six hits in seven innings against the Pirates. (Pablo Martinez Monsivais/AP)

After his Washington Nationals squeaked by with a 3-2 win over the Pittsburgh Pirates on Monday night, Manager Dave Martinez plopped down in his chair at his postgame news conference and immediately offered his answer to a question nobody had a chance to ask.

“That was exciting,” Martinez said. “We got to start scoring runs when we can. They’re playing well. They really are. But when we have a chance to put teams away, we have to start putting teams away. We really do.”

Martinez’s team had just won consecutive games for the first time in two weeks and just the third time since it started the season 4-0. His starter, Tanner Roark, had allowed just two runs in seven innings against a first-place team mounting an unexpected charge. But the rookie manager was not happy. He was exhausted, he was relieved, and he was concerned.

Like so many other days this season, the Nationals held a one-run lead when their starter departed after an outing worthy of a win. As in so many other April games, the lead could have been bigger, and because it wasn’t, the exhausted arms at the back of the bullpen — in this case, Ryan Madson and Brandon Kintzler — worked again. Though they finished April on a relative high note, having climbed back to three games under .500, the Nationals are white-knuckled and just hanging on because the offense can’t seem to sew a cushion.

The Nationals have played 10 one-run games in their first 29. They have won two of them. Three of their relievers, including Madson and Kintzler, have appeared in more than half of their games.

“If we start scoring runs, we can give these guys days off,” Martinez said. “But we’ve played so many one-run games already, it’s scary. It really is.”

The Nationals entered Monday’s game at Nationals Park with the third-worst batting average with runners in scoring position in the National League. Chance after chance to build leads — and crucially, chance after chance to build on them late — slipped away. But the first chance the Nationals mounted Monday against Pirates starter Jameson Taillon did not.

With two on and two out in the second, Wilmer Difo hit a groundball up the middle to score a run. Difo is filling in at third base until Anthony Rendon returns from his bruised big toe, which could be sooner than later. Without Rendon, Daniel Murphy and Adam Eaton, this lineup was bound to produce fewer runs than normal. Without them, this lineup cannot afford to waste scoring chances, which is exactly what it has been doing this month.

In that way, the chance the Nationals squandered in the third was illustrative of their April. After Trea Turner doubled to lead off the inning, struggling Ryan Zimmerman chopped a ball weakly to short that didn’t advance Turner. Zimmerman is 0 for his last 10.

“I just want to see, like, better contact — moving the ball,” Martinez said of his lineup with runners in scoring position. “. . . We score a lot of runs, we typically hit the ball up the middle. Difo, big hit up the middle. When you got runners on base, try to stay up the middle.”

The Pirates intentionally walked Bryce Harper, not willing to give him a chance, more willing to face Howie Kendrick and Matt Adams. Kendrick and Adams struck out.

Kendrick and Adams have been key parts of this team’s success, and the Nationals would be far worse without them. But they are not Rendon or Murphy, and they can’t protect Harper like either (or both) of those players could. The Nationals entered Monday with the second-worst average in the fourth spot in their lineup in the majors — .207. It dropped Monday.

As a result, Harper walked 38 times in March and April, second all time to Barry Bonds, who walked 39 times by the end of April in 2004. Bonds set the record for walks in a single season that year, which started almost a full week after this one, on April 5. But Harper is also struggling, and swinging at the first pitch more often than he does when things go well. He is 5 for his last 35 with 17 walks in that span, and this lineup needs him so desperately that he has yet to have a day off this season, though he could probably use one to reset himself in this week-long slump.

“They’re walking him,” Martinez said, “and he’s a little frustrated.”

But the more others contribute with runners in scoring position, the less pressure falls on Harper. Roark and Turner joined Difo by singling with runners in scoring position Monday. The Nationals had 54 hits with runners in scoring position in 28 games entering Monday — or fewer than two per game. Monday, that average went up, but a few more squandered chances left a one-run lead to the bullpen yet again.

“I pray for a lot of runs,” Kintzler said. “It’s just the way it’s going right now.

Not only did Madson and Kintzler each work for the 15th time this season, but they had to do so with no margin for error. Needing to be at their sharpest while at their most fatigued, both worked scoreless innings to secure the win.

For the first time in two weeks, the Nationals are on a winning streak. But their manager thinks his beard is graying. Their relievers hope their arms aren’t fraying. Even after they won back-to-back games, the Nationals are hanging on for dear life.