Chicago Cubs miss prime opportunity to gain ground in division race. 3 takeaways from sweep in San Francisco.

SAN FRANCISCO — Riding a three-game sweep into the second leg of a three-city trip, the Chicago Cubs positioned themselves to put pressure on the Milwaukee Brewers heading into the final four weeks of the regular season.

They couldn’t build off their success in Anaheim, Calif., however, during their series against the San Francisco Giants, who handed them a 4-3 walk-off loss Thursday at Oracle Park to complete a sweep of the Cubs. Left-hander Shota Imanaga allowed three runs in seven innings, all coming on a pair of home runs by Willy Adames, while the Cubs (76-58) couldn’t get much going off Giants right-hander Logan Webb and the bullpen.

Manager Craig Counsell, frustrated by the strike zone, was tossed by plate umpire David Rackley after Ian Happ struck out looking to end the top of the third inning.

“I thought he had gotten off to a rough start with balls and strikes, frankly thought it continued for both sides actually,” Counsell said of his third ejection of the year. “Look, we’ve got to score more. Maybe squeak out a game like that, but you’re going to have to pitch really good to win a game when you’re scoring that many runs. We didn’t help our pitching staff out enough by getting some runs on the board.”

As the Cubs head to Denver to try to salvage the trip at Coors Field, here are three takeaways from their disappointing series versus the Giants.

1. Cubs can’t avoid first three-game sweep of the season.

The Cubs have done a good job of finding ways to salvage series and not go on extended losing streaks.

They came into Oracle Park being the only team in Major League Baseball this season not to be swept in a series of at least three games. That changed Thursday. Before being handed the walk-off loss, opponents’ only sweep of the Cubs came when they dropped the two-game Tokyo Series against the Los Angeles Dodgers in Japan to kickstart the season in mid-March.

There is added sting with the sweep after the first-place Brewers lost the last two days at home to the Arizona Diamondbacks. A chance to cut into their deficit instead has the Cubs sitting 6½ games back in the division and just one ahead of the San Diego Padres for the top National League wild-card spot.

“We’ve been really resilient,” Happ said. “Obviously coming off a sweep and then getting swept, it’s a little bit frustrating, and for us taking a lot of pride this year and not letting that happen, even when we struggled a bit taking one from a series. (The Giants) are playing good baseball. They just went in and took two of three from Milwaukee, and they’re playing well. So move on from this one and get the next one.”

The three-game losing streak matches the Cubs’ longest of the season (May 6-9 and June 22-24).

2. Collective offensive inconsistencies continued.

A 12-run outburst Saturday against the Los Angeles Angels suggested the lineup was perhaps turning a corner into a more explosive group, something they showed often in the first half.

But that performance is one of only two games since Aug. 9, a stretch of 17 games, the Cubs scored more than four runs. The Cubs tallied only eight runs over the three games against the Giants and didn’t put up more than three in any of them.

“We didn’t capitalize on our run-scoring opportunities, I mean, there’s creating more run-scoring opportunities, of course,” Counsell said. “But … when we had chances to put a good number on the board, more than a one, we didn’t. We put up a zero.”

Kyle Tucker continues to look better at the plate, an encouraging sign amid otherwise largely disappointing production from the lineup. He had a two-hit day Thursday, part of a stretch that has seen him hit safely in six straight games in which he’s 9-for-22 (.422) with five runs, two doubles, three home runs and seven RBIs.

“It’s really tough because it’s a team sport, but it’s pretty individual at the plate,” Happ said. “Guys are going through their own stuff. Everybody has their own plan against the pitcher. There’s definitely talk down there in the cage about what different guys are trying to do and trying to learn from each other, but you have to go up there and have your own at-bat.

“It’s been a little bit like this of some tough games where we haven’t scored as many as we wanted to, but it’s a really good offense, and it’s a group that has the ability to do that. I’ve seen it earlier in the year, so just finding a way to keep having those good at-bats and drive runners in.”

3. With a slim margin for error, little moments add up.

The Cubs’ inability to give themselves an offensive cushion makes mistakes feel bigger.

Matt Shaw, representing the go-ahead run, got too far off second and was doubled up to end the eighth inning Thursday on Michael Busch’s liner to second baseman Casey Schmitt. The night before in a 12-3 loss, Shaw couldn’t hold onto a throw from Pete Crow-Armstrong on a tag attempt of Rafael Devers at third that would’ve ended the fifth inning Wednesday to keep it a one-run game. The next batter, Matt Chapman, hit an RBI single off Colin Rea and another run scored when Tucker’s throw from right field doinked off Chapman’s helmet to ricochet past the plate.

“Kind of some bad luck there we had,” Counsell said. “The Matt Shaw play was a difficult play, but if he can hold on to that ball and get the tag and the inning’s over, so not an easy play, but if we make that, that’s still a 4-3 game, and we’re going the next inning.”