When Theo Epstein traded Boston legend Nomar Garciaparra to the Cubs on July 31, 2004, the former Red Sox general manager sounded more pragmatic than poetic.

“We lost a great player in Nomar Garciaparra, but we’ve made our club more functional,” Epstein said that day, with the Red Sox 10 games over .500. “We weren’t going to win a World Series with our defense.”

As it turned out, trading Garciaparra in a four-team deal that brought shortstop Orlando Cabrera and first baseman Doug Mientkiewicz to the Red Sox led to a World Series title and made Epstein Boston’s new baseball folk hero.

Almost 15 years later, Epstein faces much different circumstances as Cubs president but the same need to apply bold logic before this season slips away.

Since May 14, the Cubs are 20-25 and just finished their first losing month since May 2017 — a month that exposed the roster’s acute depth issues.

The Cubs can cling to the status quo with proud and popular veterans responsible for averaging 95 victories per year since 2015. This team can still win the National League Central and perhaps even a playoff series. But it requires a quantum leap of faith to envision the Cubs planning a championship parade without Epstein daring to intervene.

Or, to put in the context of the Garciaparra trade, you don’t have to be immersed in analytics to believe the Cubs aren’t going to win a World Series with their defense. Or their erratic baserunning. Or their inability to manufacture runs without hitting the ball over the fence.

Lapses in the field and on the bases occur too often for the Cubs to check off those boxes every championship team needs to do: defense, base-running and situational hitting. An offense Epstein declared broken after last season remains too defective to trust against playoff-caliber pitching.

And it starts at the top with Kyle Schwarber, still a square peg in a round hole batting leadoff, no matter how much apologists spin his on-base percentage. Either put Schwarber’s power bat fifth or sixth or ship him to the American League.

Getting closer Craig Kimbrel provided structure to the bullpen and a statement to the clubhouse about ownership’s commitment to another title. But let’s face it, Kimbrel became more affordable to the Cubs simply because Ben Zobrist went on the restricted list. The Cubs spent the money budgeted for Zobrist on Kimbrel, lessening the burden of his three-year, $45 million deal. Signing Kimbrel was smart and sensible and offered the Cubs a solution to a glaring problem, but it was hardly unexpected after Zobrist’s exit.

Could the Cubs benefit from a trade nobody expects? Would promoting Robel Garcia, the 26-year-old with 21 home runs in 69 games in the minors, shock the system enough to resonate?

The standings suggest the answer is yes. A major deal before the July 31 deadline would give the Cubs a different look and a needed jolt.

Nobody’s suggesting trading a starting pitcher — particularly not Adbert Alzolay — or one of the Core Four position players: Javier Baez, Kris Bryant, Anthony Rizzo or Willson Contreras. But beyond that quartet, the Cubs should consider trades that allow them to change their lineup and the scope of their attack.

The bullpen needs a left-handed reliever too. As they say, the Cubs will have to give up something to get something. The price for Whit Merrifield, the Royals’ All-Star leadoff man, might be out of the Cubs’ range if it includes either top infield prospect Nico Hoerner or catcher Miguel Amaya. But Epstein at least should ask. It falls under the category of due diligence.

Start by seeing what Schwarber might bring in return. Schwarber always will hold a special place in franchise lore, but this is no time to be sentimental.

Shop Addison Russell aggressively. Coincidence or not, the Cubs have played below .500 since activating Russell on May 8. Maybe both sides would benefit from a change of scenery.

Gauge interest in center fielder Albert Almora Jr., who is tremendous defensively but has yet to gain manager Joe Maddon’s confidence offensively. The thought here is that Almora possesses enough skills to thrive in the majors as an everyday player — but the Cubs so far have disagreed.

Tyler Chatwood probably won’t draw much interest, but it can’t hurt to explore. Same goes for Mike Montgomery, who has made no secret he prefers starting to relieving and might appeal to a team looking to bolster its rotation.

Don’t forget former first-round pick Ian Happ at Triple-A Iowa, even if Happ has given the Cubs ample reason to. If Happ, Schwarber, Russell and Almora had performed up to their capabilities, the need for a shake-up might be moot.

Yes, selling low on underachieving players is a concern. But so is entering October with a roster unable to compete with an elite team such as the Dodgers — which is all that should matter.

As fun as it can be, this season at Clark and Addison isn’t about finishing in first place in the NL Central. It’s about beating the Dodgers for the pennant and then the Astros or Yankees or whoever emerges from the American League.

It’s about winning the World Series, something the Cubs look incapable of doing unless Epstein dares to get creative.

David Haugh is a special contributor to the Chicago Tribune and co-host of the “Mully and Haugh Show” weekdays from 5 to 9 a.m. on WSCR-AM-670.