Is Cubs’ bullpen deep enough and strong enough to carry staff all season?

The Cubs aren’t getting Jacob deGrom at the trade deadline. They might not have the prospects to land any starting pitcher they can be certain will offer an improvement over, say, Kyle Hendricks with his command, Tyler Chatwood without so many walks or Jose Quintana when his curveball is dancing where he wants it.

Team president Theo Epstein suggested last weekend that the Cubs aren’t banking on Yu Darvish at this point. Sixth starter Mike Montgomery already is in the rotation. And the seventh starter was on display for all of 3 1/3 innings Monday against the Diamondbacks.

But despite the pounding Luke Farrell took in a 7-1 loss in the opener of a four-game series, the Cubs still have best record in the National League despite a $350 million starting rotation that has been among the worst in the majors this season.

That raises two important questions for the final two months of the regular season:

What if the rotation doesn’t get much better the rest of the way, either through a trade or improved performances?

Can the bullpen-heavy formula that got the Cubs this far carry them the final 60-plus games and into October, especially with the increasing production from the lineup?

‘‘Absolutely,’’ reliever Steve Cishek said.

The key, he said, is the quality of the depth in a bullpen that added veteran swingman Jesse Chavez in a trade last week and already was able to go 10 to 12 deep because of Class AAA depth that has included left-hander Randy Rosario and right-handers such as Anthony Bass, Farrell, Justin Hancock, Dillon Maples, Cory Mazzoni and James Norwood.

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What’s expected to be a short-term biceps injury to closer Brandon Morrow only should make him fresher down the stretch, Cishek and manager Joe Maddon said.

‘‘Depth-wise, this is one of the best bullpens in baseball, for sure,’’ Cishek said.

But if it’s a formula the Cubs can take all the way into the final round in October, they will be pioneers: a team that will have spent essentially an entire season riding a strong bullpen the way many teams have been able to do successfully in the playoffs in recent years.

‘‘The thing is, though, you get into those really head-banging games in September, and then you don’t know how everybody’s going to react at that point,’’ Maddon said of the Class AAA shuttle crew in particular. ‘‘And guys get tired. When fatigue sets in, it’s hard to reset. So you’re really trying to avoid fatigue because once fatigue sets in and you have a couple of bad moments, it’s hard to just throw that in the garbage can and come back mentally and physically.’’

That has been Maddon’s concern all season, he said. He has tried to spread the workload to preserve the bullpen until a rotation he once called the best he has had in his time in Chicago arrives in its usual form.

But it has been four months, and the starters are averaging barely five innings. They lead the majors in walks and have the fourth-fewest strikeouts in the National League.

And Fangraphs.com makes a compelling case that they’re on pace to become the worst rotation in Cubs history.

‘‘We need more length out of our starters in order to maintain the integrity of the bullpen,’’ said Maddon, who has used four position players for five appearances in the last four days and pushed Quintana to 121 pitches because of bullpen concerns Sunday. ‘‘It’s just going to be hard to do otherwise.’’

But will they have a choice? And will the expanded roster in September make it a little more plausible?

Setup man Carl Edwards Jr. is confident the bullpen can handle whatever the championship needs might be.

‘‘We’ll just go out there and just try to do what we’ve been doing all year,’’ he said. ‘‘I love our bullpen. . . . It’s magic.’’

It might have to be.