To win the World Series, who can the Cubs least afford to lose?

When Joe Maddon saw an irregularity in John Lackey’s body language Sunday, he made a beeline for the mound and removed his starter. The manager knows that small problems can turn into big problems quickly.

It wouldn’t be the end of the world if the Cubs were to lose Lackey, who has a stiff right shoulder. That’s not a knock against the big right-hander. It’s a reflection of how talented the roster is and a recognition that some players are more valuable than others. It’s why some get paid more, though to this day no one has been able to explain Edwin Jackson’s contract.

But as the Cubs march toward the playoffs, it raises the question of which player the team could afford to lose if it wants to win a World Series this season. These are the kinds of talk-radio debates that come up when it’s August and a team is leading its division by 12 games.

The discussion comes down to Dexter Fowler and Jake Arrieta. I know that Kris Bryant and Anthony Rizzo are locked in a battle for the National League Most Valuable Player award. Their statistics are terrific. Kyle Hendricks has been the team’s best pitcher.

But we saw how the Cubs are when Fowler, the leadoff hitter, isn’t around to get on base and give Rizzo and Bryant someone to drive in. The team is 58-26 when he has played this season and 15-17 when he hasn’t.

This is a good time to remind you that the Cubs weren’t even supposed to have Fowler in 2016. He was primed to sign with the Orioles and then had a spring-training change of heart. Where would they be without this guy? Probably battling with the Cardinals for the division lead.

If the Cubs want to win a World Series, they’ll need Arrieta at his best in the playoffs. There’s really no wiggle room here. If he were lost to injury, you’d have a playoff rotation of Jon Lester, Hendricks, Lackey and Jason Hammel. Not nearly good enough. The Cubs were not the same team when Arrieta was off his game this season. When they struggled in July, he was 0-3 with a 4.88 earned-run average.

True, we don’t know how the Cubs would be without Bryant and Rizzo. The team hasn’t had to deal with their absence. But we’ve seen what they are without Fowler, and we’ve seen what they are when Arrieta struggles.

I’m going with Arrieta. You need a shutdown starter in the postseason. No Arrieta, no World Series.