CINCINNATI — Chicago Cubs manager Joe Maddon has a decision to make at second base come next Wednesday when his team plays the Pittsburgh Pirates in a winner-take-all wild-card game.

With right-handed Gerrit Cole most likely on the mound for the Pirates, should Maddon start lefty Tommy La Stella or defensive whiz Javier Baez? Or maybe he shouldn’t overthink it and instead play the hottest hitter in the National League right now, Starlin Castro.

“He is playing with such tremendous focus right now,” Maddon said after watching Castro go 4-for-5 in a 10-3 win over the Cincinnati Reds on Wednesday night. “He’s playing at the top of his game. He’s playing a complete game of baseball right now.”

Castro is simply a different player than the one that struggled for much of four months before being benched and forced from shortstop to second base. He bottomed out but never sulked. Instead he made changes to his approach at the plate as well as his swing. The results have been eye-opening: Castro hit .426 in the just completed month of September.

“It’s unbelievable,” he said. “That’s why I trust the people that say, ‘You never stop learning in baseball.’ Now I know it’s true. Sometimes you think you know everything, and you don’t.”

Castro has always been honest about his struggles but this is the first time he has admitted to being so stubborn. He closed up his stance a bit, moved closer to the plate and now is driving balls to left and left center. Previously, he would roll those pitches over to shortstop.

“I feel great,” Castro said. “I never put my head down. … It means more for me because we got into the playoffs.”

Those playoffs are approaching and Maddon hasn’t yet made his decision on a starter for next week’s affair. Before Wednesday’s game against the Reds, he indicated everything is on the table.

“I have thoughts that I’ve thrown out there,” Maddon said. “I give my stuff to the [stat] guys to mull over. And to throw back and shoot holes into what I’m thinking.

“I don’t have any conclusions drawn yet. We’ll see how it comes out of the oven and figure it out from there.”

The decision comes down to many factors. Is the better defender best to start the game or come in later with a lead? How much offense is left on the bench if the hottest September bat isn’t in the lineup?

“I told my guys what I’m thinking,” Maddon continued. “They’ll run through the simulations and bring it back to me. … I know what I think I want to do. I want to find out how it plays out.”

Castro must be making it tough on him. The bottom line is all three infielders could see action at second as whoever starts the game isn’t likely to finish it unless the Cubs are blowing out the Pirates. If Castro helps the Cubs to a lead, Baez would be the defensive replacement while La Stella might the best pinch-hitter of the group. Castro’s strength isn’t either of those two things, though he made a highlight-reel play in the fifth inning on Wednesday, diving into the outfield near second base before throwing out Brayan Pena.

“That’s what I love, watching him play right now,” Maddon said.

Castro thought the Cubs would be just OK this year and would really take off next season. He also thought he would be the starting shortstop all year. Things change and slumps happen, even prolonged ones. But Castro has come out of it after looking in the mirror and realizing what he had to do. He has been through it all and is looking forward to his first playoff experience — finally.

“I don’t have that decision,” Castro said of starting in the game.

But Maddon does. And he’ll need to make one soon.