A crowd of 40,551 at Wrigley Field was rocking when Patrick Wisdom crushed a go-ahead 3-run homer to the left field bleachers in the 2nd inning Sunday.

That was one of the Cubs’ few high points on the day; Wisdom also hit a 2-run blast in the 8th inning.

Cincinnati toppled the Cubs 8-5, completing a 3-game sweep that dropped the North Siders a season-high 8 games under .500.

“It was an ugly weekend for us,” starter Drew Smyly said. “The Reds came in and beat us up.”

In the 3 games, the Reds outscored the Cubs 25-10 and outhit them 45-19 — including 19-2 on Friday when Cincinnati carried a combined no-hit bid into the 8th inning.

Smyly has been as dependent a starter as any for the Cubs this season, alongside Marcus Stroman and Justin Steele. Entering the day, he pitched at least 5 innings in 9 straight starts, allowing no more than 2 earned runs in each.

Sunday, he lasted 4.2 innings, allowing 5 runs on 7 hits and 2 walks. It tied for his shortest outing of the season — his season debut April 3 in Cincinnati.

“They just grind people; they just grind the pitchers,” Smyly said of the Reds. “They’re not gonna slug you and hit a bunch of homers, but they don’t chase. They take their singles, they steal bases. You saw it all weekend.”

Three of the Reds’ 44 hits this weekend left the ballpark, and 2 came off Jonathan India’s bat in Saturday’s game.

That small-ball approach was evident Sunday, as Cincinnati applied pressure on the basepaths to help manufacture runs. A few examples:

• In the 2nd inning, Stuart Fairchild doubled on a line drive to Ian Happ, who came up short on a diving attempt. Moments later, he stole third base and then scored on a Nick Senzel single through the Cubs’ drawn-in infield.

• In the 5th, Matt McClain hit a 1-out single to right field. He stole second, advanced to third on a pickoff throwing error by Smyly and eventually scored on a double.

“They make pitchers work for sure,” Smyly said. “They got the most of us this weekend. [At the] same time, India hit a good ball hard down the line. But I mean, just what I’m talking about. They’re not really barreling stuff. They’re just kind of shooting you and getting guys in scoring position.

“You can argue that that makes it harder on pitchers than having a bunch of guys trying to hit homers.”

The Cubs entered the Sunday last in the NL Central and with the worst winning percentage in the National League. They’ve lost 4 straight games — 1 shy of their longest skid of the season — and on Monday they welcome the MLB-leading Tampa Bay Rays to Wrigley for three games.

How do they not press while in a rut as extended as this one?

“I think you just have to focus on more individual stuff — one thing at a time,” Happ said. “Whatever the matchup is with the pitcher tomorrow, focus on your plan, your approach, how our pitching staff is gonna attack the individual hitters.

“Those are the important things. Just do that every day. Results will start to follow. It’s just a matter of getting a couple of them to click in a row.”

Said Wisdom: “We still have a lot of belief in this clubhouse and we believe in one another and so I think that’s key for us to keep going and not lose that faith. It’s baseball so we can come out tomorrow and have a stellar day and that can be the turning point for us. We still have a lot of belief in one another.”

Notes

— Reliever Brad Boxberger played catch on Sunday for the first time since landing on the 15-day injured list May 15 with a right forearm strain. Manager David Ross said on Tuesday further evaluation of Boxberger’s injury revealed no structural damage.

— Cody Bellinger has been tracking pitches in the batting cage this week and improving but has not resumed running yet, according to Ross. Bellinger injured his left knee making a leaping catch during the Cubs’ series in Houston and went on the injured list May 19.

“Feeling better every single day, slowly but surely,” Ross said. “He’s able to do a lot of little things but not quite in the running yet. Doing some pool work and some things.”

— Codi Heuer pitched Saturday for Triple-A Iowa on his rehab assignment and finished the outing feeling good physically, the Cubs said. Heuer, who is coming back from Tommy John surgery, tossed 1.1 scoreless innings with 4 strikeouts.