Gabe Kapler stood Tuesday night on the dugout steps as a game that was a pitch away from becoming a Phillies win quickly turned into a losing rout.

The manager, after relying heavily on his bullpen the previous two days, expected Tuesday night’s 10-6 loss to be a prime chance to rest his top relievers. Aaron Nola was on the mound, so the Phillies -- even though they were playing the rival Nationals -- hoped the burden would be eased on the bullpen.

Kapler, after resting Pat Neshek, Adam Morgan, and David Robertson, hoped he could piece together the final innings with some of the team’s less-reliable arms. The likely plan was this: Aaron Nola for seven innings, followed by Seranthony Dominguez and Hector Neris tackling the final six outs.

But the late innings, Kapler learned, can be difficult to plan. The manager’s strategy failed and the Phillies were bitten when their bullpen collapsed without the support of three of their best relief pitchers.

Jose Alvarez, the anonymous eighth pitcher in an eight-man bullpen, allowed four runs in the 10th inning. Kapler, his bullpen exhausted, could only stand there and watch.

“I think we executed our game plan,” Kapler said. “Would we like to have had a full bullpen? Absolutely.”

Neshek, who leads Phillies pitchers in appearances, was off after pitching three of the team’s last four games. Robertson and Morgan were both off after pitching on consecutive days. Kapler expects to lean heavily on the three pitchers throughout the season, so it was hard to blame him for trying to find them rest.

After a five-run Phillies lead became a one-run lead in the seventh, Kapler relieved Aaron Nola earlier than he hoped and used Dominguez to record the final two outs of the seventh on four pitches. That pushed Hector Neris into the eighth inning, but he entered on a double-switch as the Phillies hoped he could handle the final two innings on his own.

But Neris needed 30 pitches for a laborious eighth inning, so Kapler pivoted to Edubray Ramos for the ninth inning. Ramos had not pitched in six days, but he still found himself just one strike away from locking down the save. He hung a slider and Victor Robles slammed it for a tying homer to left field.

“I’ll say this about Ramos,” Kapler said. “He looked pretty effective up until that very last pitch.”

The bullpen would not hold onto the tie for long as Juan Soto tagged Alvarez with a towering three-run homer in the 10th. Robles returned with an RBI double to cap the four-run inning. By then, it was obvious that the Phillies’ bullpen is simply not deep enough to get by with three of their most trusted arms resting on the same night.

Tommy Hunter, a steady presence in last season’s second half, remains in Clearwater, Fla., with an arm injury and his return does not seem imminent. His absence was magnified on Tuesday as the Phillies were ultimately without four of the relievers who allowed them to believe during spring training that their bullpen would be a strength.

That unit, if it ever gets to full strength, still could be a strength. But as Kapler stood Tuesday night on the dugout steps and watched his patchwork 'pen collapse, it was evident just how thin the bullpen is.

“We knew that we had to give those guys a blow,” Kapler said. “We have eight guys in the bullpen who we know we are going to give important innings to, so we trusted that we were going to be able to get the job done with the guys we had.”