CINCINNATI — Outside of Wrigley Field, Cubs left fielder Ian Happ is most productive at Great American Ballpark. He entered the game Friday against the Reds with 18 home runs and a 1.002 OPS there, his best marks at an opponent’s park.

He added a homer in the third inning, giving him the sixth-most by a visiting player in the stadium’s 24-year history. So why on earth did Michael Busch, who had reached on a walk in the ninth inning, try stealing second base with two outs and Happ representing the tying run?

After being called safe, Busch was ruled out on a video review, and the Cubs lost 6-4.

“That was a dumb play,” manager Craig Counsell said. “It was stupid. I’ll take responsibility for it.”

“That’s just inexcusable on my part,” Busch said. “Gotta make sure if I’m taking that base that I make it 100%. We have a good hitter up in Happ, and that can’t happen.”

It wasn’t one of the biggest reasons the Cubs lost. Those were right-hander Clay Holmes walking five — including three in the Reds’ game-turning three-run sixth — and the hitters going 2-for-10 with runners in scoring position and leaving nine men on base overall.

“Can’t walk the leadoff guy there in the sixth inning,” Holmes said. “The walks hurt. The past three outings, I haven’t been efficient.”

Fortunately for the Cubs, the Phillies also lost, keeping the teams tied for the top spot in the National League wild-card race, with the Cubs holding the tiebreaker. Unfortunately for them, the Padres had a chance to make it a three-way tie late Friday.

Swanson returns to action

After a rehab assignment that never happened and two simulated games, shortstop Dansby Swanson returned from a strained left oblique. He looked no worse for wear from the start.

Reds leadoff man Carlos Jorge hit a pop fly down the third-base line that Swanson chased all the way into foul territory next to short left field. He slid on the warning track as he neared the wall but couldn’t make the catch. The official scorer ruled it no play, but that couldn’t have been further from the truth.

If anyone had concerns about how Swanson’s body would react to real game action, that play should’ve allayed those fears.

Swanson missed a month with the injury, and his rehab assignment this week with Triple-A Iowa got rained out, forcing the Cubs to get creative. They flew in two minor-leaguers to pitch to him in a sim game Wednesday, during which Swanson also played in the field. He got in another workout Thursday at Wrigley Field before the team left town.

“We’re our best team when Dansby’s out there,” Counsell said. “We’re our best defensive unit, for sure. The rehab part got screwed up with the weather. We’re excited to have him back.”

Swanson batted ninth, going 1-for-3 with a walk and a run scored. His hit was an infield single on which he beat the throw from Elly De La Cruz deep in the hole at short.

Playoff rotation can wait

With only eight games left in the regular season after Friday and a playoff berth likely in their future, the Cubs are starting to think about how they’d like to line up their postseason rotation. But thinking is all that they’re doing.

“We’ve got a lot to accomplish before that,” Counsell said. “Do you start thinking about those things? Absolutely, you have to think about them. But my experience is that those decisions change many times. So you just kind of position yourself for possibilities.”

Counsell refuses to look at much beyond the game at hand.

“Worry about today; that’s all we can do today,” he said. “I know that’s coachspeak, but it’s how you have to work as athletes and coaches. Getting ahead of ourselves for those things is useless.”