Washington second baseman Danny Espinosa loses the ball as Matt Carpenter slides into second base in the first inning of Wednesday’s 4-2 loss to St. Louis. (John McDonnell/THE WASHINGTON POST)

The Washington Nationals’ offense may have reached its lowest depths of ineffectiveness in one telling moment of Wednesday’s 4-2 loss to the St. Louis Cardinals. The lineup, which scratched out its first run in 20 innings on a pleasant afternoon at Nationals Park, had a prime opportunity late in the game to prevent a sweep at the hands of the team that ended its season last October.

Instead, the Nationals lost their ninth of 12 games and left Manager Davey Johnson looking to make more changes to the lineup.

In the seventh inning, with runners at first and third base and trailing by two runs, Johnson sent pinch hitter Steve Lombardozzi, one of the team’s lesser-used hitters, but an effective one nonetheless, to the plate.

Cardinals reliever Joe Kelly was struggling, allowing back-to-back singles and throwing three straight balls to Lombardozzi. Once Kelly fought back to 3-2, Johnson called for a hit-and-run, an anxious attempt both to prevent a double play with catcher Jhonatan Solano at first and to potentially net a game-tying run with a hit.

Instead, Lombardozzi, who doesn’t strike out often, swung and missed on an outside 94-mph fastball — and it was an ideal pitch to throw out Solano at second base to end the inning.

“All the little things go against you,” Johnson said.

The giddy joy of last season and a winter of sky-high World Series aspirations seemed so distant. Stephen Strasburg, who produced seven effective innings Wednesday after a rough beginning, was betrayed by a lineup struggling. The Nationals fell to 10-11, the first time they have been under .500 since the final day of the 2011 season.

“We need to jumble it up and we need to switch the mojo a little bit,” outfielder Jayson Werth said. “I think somebody was talking about Phil Jackson the other day. We need to call him up, have him come in here and burn some sage or something. We’re not very feng shui right now.”

The Nationals continue to be bothered by the losses but again preached patience. Their results are magnified, some players believe, because they are dealing with expectations for the first time and because it’s only April. While some players may not admit it, Johnson sees a team playing aggressively to a fault because they want to succeed.

“It’s frustrating,” he said. “We’re just not doing the things we’re capable of doing. Guys are trying to do too much. [Ian Desmond] looked like he was trying to hit the ball to the light tower. Little things where guys are trying to create something that’s not there yet.”

Said Werth: “They always say you’re better lucky than good and we’re neither right now. We’ll be all right. Just things aren’t going our way and we’re not playing real good on top of it. We need to, might need to switch it up a little bit.”

Johnson said he would start Lombardozzi, who is hitting .345 in 29 at-bats, near the top of the order on Thursday as part of his effort to jump-start the lineup. Lombardozzi could play third base, which has been manned by rookie Anthony Rendon since he was called up Sunday. Johnson also suggested possibly moving Werth from the second spot to the heart of the order.

“Sometimes you do have to shake stuff up,” leadoff hitter Denard Span said. “Maybe somebody from the bench can come in with some energy and do something that might rile us all up.”

By the end of the first inning, Strasburg had put the Nationals in a seemingly insurmountable hole. He threw first-pitch strikes to only three of the Cardinals’ first seven batters, at-bats which resulted in weak hits, a walk and three runs.

For the rest of the start, Strasburg was efficient and pounded the strike zone. He fired first-pitch strikes to six of the next nine batters he faced and allowed only two more hits. He scored the Nationals’ first run since the fourth inning of Monday’s game, after he singled to lead off the sixth inning. Bryce Harper, the lone shining star of the offense, grounded out to score Strasburg from third base. Werth added the only other run with an eighth-inning homer.

The Nationals’ sleepy offense has searched for answers for nearly a week. A lineup loaded with talent, even with Ryan Zimmerman and Wilson Ramos on the disabled list, has failed in potentially productive situations.

Desmond, hoping to reach base against left-hander Jaime Garcia, bunted for a single in the second inning.

Once at first base, he took off for second on Garcia’s first move. The left-hander saw it and threw to first but Desmond raced into second to narrowly beat the throw. The play screamed of aggressiveness. He was, however, stranded on the bases after a flyout and strikeout. “Just trying to get something going,” he said. “A little spark here or there.”

After Werth’s home run in the eighth cut the deficit to 4-2, Harper drew a one-out walk. But Adam LaRoche — inserted as a pinch hitter after Johnson left him out of the lineup for a mental break — struck out, his fifth straight dating from Tuesday. Desmond then struck out on three straight fastballs from Trevor Rosenthal that clocked between 97 and 98 mph, the final swing a monstrous uppercut whiff.

“We’ve been pressing,” Werth said. “We’ve been trying to do too much. That’s a common side effect. It’s just one of those things. It’s early. It’s not as bad as it seems. Somebody said last night it feels like we’re 0-20, but it’s not that bad. We’re only one game under .500 and it’s April.

“We’ll be all right. What we’re going through, it’s the first time this team has dealt with expectations, and there’s something to be said about that. But we’ll adjust. The league has adjusted to us, we’ll adjust to the league. We’ll be fine. We’ve got too much talent.”

Note: Ramos, who has been on the disabled list since straining his hamstring running out a groundball on April 13, hopes to begin his rehab assignment on Friday, Johnson said. Before the injury, Ramos was 6 for 20 with three walks and two homers.