Brewers catcher Manny Pina (9) beats the tag by his Nationals counterpart Matt Wieters to score the first run of the game in the second inning Tuesday night at Nationals Park. Milwaukee went to an 8-0 win. (Toni L. Sandys/The Washington Post)

The second act of Edwin Jackson’s career with the Washington Nationals is two scenes deep and, after the Nationals’ 8-0 loss to the Milwaukee Brewers on Tuesday night, can be boiled down to the 91st pitch in each.

Last week, pitch No. 91 in Jackson’s return to the Nationals was his last, and it secured the third out of the seventh inning, an uplifting performance that earned him a win in a 4-3 victory over the Los Angeles Angels. On Tuesday, Jackson, reverting to the command difficulties that have plagued his winding career, threw his 91st pitch three innings earlier. It was a 1-2 fastball, and Travis Shaw belted it just over the wall in left-center field at Nationals Park for a three-run home run.

“It’s just a matter of making a pitch,” Jackson said. “If I make one pitch on that 1-2 count, then it’s a different scenario. It’s a different ballgame that we’re talking about there.”

The blast put the Brewers (54-48) ahead 5-0 in the fourth inning. Washington (59-39) didn’t respond with an offensive onslaught to mask the fifth starter’s troubles as it did so often when Joe Ross filled the role earlier this season. Instead, Zach Davies, who entered with a 4.76 ERA and 1.486 WHIP, muzzled the Nationals’ bats over 7⅔ innings to steer the reeling Brewers to their second win in nine games.

A few hours before first pitch Tuesday, Stephen Strasburg, who exited his start Sunday in Arizona after two innings, played catch on flat ground. Minutes later, a Nationals spokesperson told reporters the right-hander, whose original diagnosis was forearm tightness, “had some nerve impingement that has been alleviated.” Where exactly wasn’t divulged. Nothing else was. Left unclear is whether Strasburg is on schedule to make his next start.

Strasburg was just the latest of the Nationals’ concerns. Eight Nationals are on the disabled list. Another, Ryan Raburn, is on the bereavement list following the death of his grandfather. Another, Enny Romero, also left Sunday’s game with back spasms.

“We’re kind of walking wounded, and our extra guys are chipping in big time,” Manager Dusty Baker said. “Fortunately for us, our main all-stars, our core guys, are healthy and doing well because those are the guys that are in a very important situation where they have to do the job. And they are doing it.

Among those core guys are Bryce Harper, Ryan Zimmerman, Daniel Murphy and Anthony Rendon. The quartet, in that order, makes up perhaps the best middle-of-the-order combination in baseball, a gantlet pitchers seldom emerge from unscathed. But Davies quieted the foursome. He mixed and matched his well-rounded arsenal with tact, allowing them just two hits and a walk in 12 plate appearances against him. The rest of the lineup went 1 for 15 with two walks against Davies as the Nationals were shut out for the third time in 12 games after going 86 games without getting blanked.

“Sometimes you got to tip your cap,” said Harper, who grew up playing with Davies and extended his hitting streak to 17 games with a double in the eighth inning after Davies exited. “He did his job tonight.”

Thrust into the fifth starter’s spot after Ross was lost for the season with a torn ulnar collateral ligament, Jackson’s final numbers in Anaheim last week were sturdy. He limited the Angels to two runs and didn’t issue a walk across seven innings. It was the kind of efficiency that has often eluded Jackson during his nomadic career. He was, however, by no means dominant. The Angels made hard contact, but the defense behind him was good and he managed to evade trouble. Jackson, appearing at Nationals Park in a home uniform for the first time since the 2012 playoffs, didn’t benefit from such fortune Tuesday night.

The right-hander issued a couple of two-out walks and tossed 29 pitches in the first inning. He threw another 25 and allowed his first run in the second. Yet, though he had thrown 69 pitches by the end of the third, he trailed only 1-0.

Then his defense failed him. The crucial mishap occurred when Davies dropped a sacrifice bunt with one out in the fourth. The ball rolled to Zimmerman, who had ample time to make the routine throw to first base, where Murphy was running over to cover. But Zimmerman’s throw went behind Murphy and bounced off his glove, allowing Davies to reach base safely.

“I just needed to lead him more or just wait till he gets to the base,” Zimmerman said. “Had plenty of time. Edwin was throwing the ball great. Just throw the ball to Murph and you never know what’s going to happen. Obviously, that one is on me.”

Two batters later, with two outs, Ryan Braun hit a groundball to Murphy’s right. The second baseman tumbled to snag it, but his flip to second base wasn’t in time, allowing Davies into scoring position and a run to score. Shaw followed with his three-run home run, his 23rd of the season, to blow the game open with four unearned runs.

Jackson lasted one more inning, forced to absorb a couple of more blows to lighten the load on a bullpen that logged seven innings following Strasburg’s early departure Sunday. They came in the form of back-to-back home runs. First, Eric Thames led off the fifth with a towering blast off the facade of the third deck in right field. Manny Piña then matched him, launching a solo homer over the wall in center field to give Milwaukee a seven-run cushion. Jackson retired the next three batters to end the second scene of his second act in Washington with 112 pitches and a loss.