Nationals reliever Justin Miller looks on as Marlins shortstop JT Riddle circles the bases after a ninth-inning home run snapped a 4-4 tie. The Nationals would rally in the bottom of the inning but go on to lose the game, 7-5, in the 10th. (Jonathan Newton/The Washington Post)

For the Washington Nationals to somehow emerge from the pit they’ve spent the past two months digging, they must minimize losses against teams they are supposed to beat. The math does not allow for those at this juncture. So after the Nationals rallied in the seventh and ninth innings against the last-place Miami Marlins at Nationals Park on Saturday night, they turned to the best reliever remaining in their depleted bullpen for the 10th.

And Koda Glover’s appearance served as another distressing example of the bullpen’s swift fall from unquestioned strength to debilitating weakness. For the third time in less than a week, the Nationals’ bullpen blew a lead in their opponents’ final at-bat. For the second time, it came with Glover, the Nationals’ fourth-string closer, on the mound. This time, the right-hander surrendered two well-placed groundballs through the infield before yielding a two-out, two-run single to Isaac Galloway in a 7-5 loss.

“I mean, it’s very frustrating,” Glover said. “It’s like you punch somebody and then you get punched twice.”

The setback’s sting was amplified considering both teams the Nationals are chasing in the National League East also lost, keeping Washington (62-62) seven games behind the first-place Atlanta Braves and 6 ½ games behind the second-place Philadelphia Phillies. It was, simply, another wasted opportunity.

It’s been six weeks since the Nationals’ bullpen was fortified. It boasted an all-star closer, three former closers and quality depth beyond that. Then Sean Doolittle landed on the disabled list, Brandon Kintzler was traded, Shawn Kelley was designated for assignment and traded, Kelvin Herrera was placed on the disabled list, and Ryan Madson — after surrendering a walk-off grand slam with a three-run lead last Sunday — joined the DL brigade. What remains is an unrecognizable relief corps.

Glover shouldn’t be the best reliever in Washington’s bullpen. A couple weeks ago he was rehabbing in the minors, waiting for his chance to provide middle-inning depth. He wasn’t supposed to pitch in high-leverage situations, but the choices are limited. The collapse began with two well-placed groundballs through the infield. Manager Dave Martinez then decided to intentionally walk JT Riddle, a .226 hitter who was 3 for 5 with a double and a home run, to load the bases with two outs for Galloway and the Marlins (49-76).

“He’s swinging the bat really well,” Martinez said of Riddle. “He’s dangerous right now…I like the matchup with Glover and Galloway right there.”

But Glover, making his fifth appearance in the majors this season, fell behind 2-0 on the light-hitting Galloway before yielding the go-ahead hit five days after he gave up a walk-off home run in Monday’s to the St. Louis Cardinals.

“I got to get the job done at the end of the day,” Glover said. “They count on me, and I should come through for them, and I haven’t two times. So it’s one of them things. Tonight’s honestly more frustrating than the other night.”

With that, Jefry Rodriguez’s solid outing and the offense’s rallies were wasted, overshadowed by Martinez’s decision-making, Daniel Murphy’s costly defensive gaffe in the sixth inning, and the bullpen’s continued struggles.

Rodriguez was chosen to start Saturday after allowing two earned runs across 22 ⅔

innings over his previous four starts — one in the majors and three in Class AAA. He was attacking the strike zone more. He was displaying more confidence in his change-up to complement his high-90s fastball and curveball. He was evolving as a starting pitcher.

Early on, the evolution was evident. Rodriguez had allowed two runs five strong innings when his spot in the lineup came up in the bottom of the fifth with Spencer Kieboom at second. Martinez’s decision: Pinch-hit for his pitcher or let him face the heart of Miami’s lineup a third time after throwing 69 pitches through five innings?

Martinez chose to allow Rodriguez, who singled in his previous at-bat, to hit. He grounded out.

Moments later, after the Nationals stranded Kieboom at second, Rodriguez surrendered consecutive singles to J.T. Realmuto and Brian Anderson to start the sixth and was lifted anyway for left-hander Tim Collins, who came on to face left-handed hitting Derek Dietrich.

“I really thought when he went out there he was still pretty strong,” Martinez said. “Two pretty good hitters get a couple hits. We decided to make the move then. But he did well, he really did.”

Collins struck out Dietrich. With two right-handed hitters due up next, Martinez emerged from the dugout again to insert right-hander Jimmy Cordero, who had rejoined the team from Class AAA Syracuse earlier in the day. Cordero induced the potential double play groundball he needed from Starlin Castro, but Murphy mishandled a high hop and the ball bounced off his glove, leaving the bases loaded. Two batters later, Riddle, smacked a line drive that a leaping Murphy couldn’t snag for a two-out, two-run single.

“I make an error right there, put us behind schedule, and then I misplay a line drive,” Murphy said. “It was a direct hand in us losing this ballgame. Two plays I should’ve made. I didn’t. And it really hurt us a lot tonight, unfortunately.”

Murphy bounced back in the seventh when he lined the 11th pitch of at-bat against Tayron Guerrero – a 100 mph fastball – for a leadoff single. Adam Eaton followed with a weak chopper to third base that a charging Anderson couldn’t corral. Guerrero then hit Matt Wieters with a pitch.

Guerrero’s next pitch was wild, allowing Murphy to score. Two batters later, Turner blooped a single to shallow center field to score Eaton and knot the game. That spelled the end for Guerrero, who left a two-on, one-out mess for Adam Conley to clean up. Conley induced Juan Soto to ground into an inning-ending double play on the first pitch. The teenage rookie, sensing the missed opportunity, slammed his helmet in frustration.

In the ninth, Justin Miller, the Nationals’ top setup man by attrition, served up a fastball that Riddle walloped into Washington’s bullpen beyond right field to give Miami the lead. Then, moments after the first-place Braves blew a 3-0 lead against the Colorado Rockies in the ninth inning, Eaton crushed the ninth pitch he saw from Drew Steckenrider to tie the game with one swing.

The fiery Eaton sped around the bases, as if he couldn’t wait for the guys behind him to pounce, but the Nationals didn’t. Wieters singled up the middle before Washington went down in order. The wasted chance proved costly as the 10th inning unfolded, and the Nationals lost a game they couldn’t afford to lose in a way that has become too familiar.