Jake Arrieta’s injury timeline could make or break Cubs’ playoff shot

Forget the Cubs’ 8-3 victory against the Mets that kept the Cardinals and Brewers at bay for at least another night in September.

The most important event for the Cubs on Tuesday happened hours earlier — before the ballpark opened to fans — when right-hander Jake Arrieta played catch for the second time since suffering an injury to his right hamstring.

Arrieta reported feeling good despite lingering tightness in his push-off leg, team officials said.

With 18 games left in a tightening National League Central race, nobody has any idea when the NL’s pitcher of the month for August will return to the rotation. It’s hard to imagine any other factor having a bigger impact on whether the Cubs can hold off the charging Cardinals (two games back) and the Brewers (2½ games out) or whether they slide out of playoff position.

‘‘I still don’t know when he’s going to be ready; I really don’t,’’ manager Joe Maddon said.

The closest thing to certainty is that Arrieta has been ruled out of the Cubs’ showdown series this weekend against the Cardinals. That would seem to make a best-case return sometime during a road series Sept. 21-24 against the Brewers.

That’s a far cry from when Arrieta said the day after leaving a start Sept. 4 that he hoped in ‘‘five or six days from now [to] get back on the bump and get back to work.’’

He already missed a scheduled start against the Brewers and is out for the next one against the Cardinals. Had he remained in rotation, his next two likely would have been against those teams, too. The Cubs already lost the first start he missed 15-2 to the Brewers on Saturday.

Arrieta was 7-2 with a 1.69 ERA in July and August before getting hurt in his first start of September.

‘‘It’s hard to lose a guy like him anytime,’’ Maddon said. ‘‘If he comes back pitching at that level, one or two starts could make all the difference in the world — and then beyond. No doubt.

‘‘And furthermore, he should be rested, which is also an attractive part of that. It’s just so hard to tell.’’

Arrieta hasn’t reached the point of scheduling a throwing session from a mound yet. His injury came only a few days after left-hander Jon Lester returned from a lat injury. Lester, who Wednesday will make his third start since the DL stint, still is working through rust that showed in his first two starts back.

Maybe that underscores the importance of what Arrieta brought to the top of the rotation the last two months.

This certainly does: Until Tuesday, the Cubs had won only twice in a week since he was hurt. That included being swept by the Brewers last weekend.

‘‘The positive of everything is we’re coming off a long two years, and we’re in first place,’’ first baseman Anthony Rizzo said, looking at the Cubs’ big picture. ‘‘Every single person [in the media] standing here right now is overlooking that. I think where we’re at right now is in an unbelievable position that we can’t take for granted.’’

That’s exactly why Arrieta at full strength for even a start or two down the stretch might make the biggest difference any player has the potential to make in the race.

‘‘Really big,’’ Maddon said. ‘‘But I don’t know if it’s going to work yet or not. . . . There’s still some time involved here.’’

Follow me on Twitter @GDubCub.

Email: gwittenmyer@suntimes.com

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