The Chicago Cubs’ formula to building a bullpen follows a distinct pattern.

Start with proven, lockdown relievers for the late-inning, high-leverage moments and fill in key spots from there. Craig Kimbrel and David Robertson became the go-to options for save opportunities during their respective tenures for manager David Ross.

And leading up to those save opportunities, Ross had Ryan Tepera and Andrew Chafin in 2020-21 and Chris Martin and Mychal Givens last year — at least until the trade deadline, when the Cubs unloaded their top relievers as part of the rebuild.

The bullpen’s struggles this season can be attributed partly to the lack of reliable veterans, forcing more matchup-based decisions for Ross. And that falls on Cubs President Jed Hoyer and his offseason decisions. He acknowledged his role in the team’s bullpen woes before Tuesday’s 7-2 win in the series opener against the New York Mets.

“If I’m being candid, I feel like I’ve put Ross in a tough spot to a certain extent,” Hoyer said. “That’s an area we’ve had so much success with. … We’ve candidly done a really good job of finding relievers that could come in and throw high-leverage innings at a relatively low cost on one-year deals. And we’ve been building bullpens that way for a while, and this year that hasn’t worked yet.

“That’s on me, and that’s put Rossy in a tough spot. It hasn’t lined up the way we expected it to.”

Brad Boxberger and Michael Fulmer haven’t been the veteran back-end staples the Cubs envisioned. It’s unclear when the Cubs will get back Boxberger, who is on the 15-day injured list with a right forearm strain. He underwent evaluation that showed he has no structural damage in his arm, according to Ross. Boxberger will continue to rest to reduce inflammation and build back up once he is pain-free.

“I don’t think it’s going to be a super long thing or have to deal with surgery as of now,” Ross said.

Fulmer has been a little unlucky this season — a 7.58 ERA, 4.23 fielding-independent pitching (FIP) and .358 batting average on balls in play (BABIP) — and it complicates how much he can be trusted in leverage spots.

“That hasn’t lined up the way we expected it to and we’ll get there,” Hoyer said. “We have a lot of power arms in the minors and in the organization and we’re going to get there, but that’s an area we had a lot of success for while. It hasn’t been an area of success this year and that’s been hard on Rossy, and that’s on me.”

How the Cubs play over the next month will affect the front office’s calculus of whether it should buy or sell before the Aug. 1 trade deadline. A 2-10 record in one-run games has hurt the Cubs’ efforts to stay near the top of the division.

“We’re going to have to dig out from that,” Hoyer said.

The most frustrating part of this 7-16 stretch is the struggles aren’t limited to either pitching or offense. The problems vacillate from game to game. And within each, pinpointing the whys behind the struggles adds another layer to the frustration.

“Is it pitch execution, is it pitch selection? Is it putting the right people in the right place to succeed at the right time?” Hoyer said. “Offensively it comes down to the same thing: Are we swinging at the right pitches, are we trying to do too much? It’s a hard thing to pull apart.

“The bullpen has been maligned for not getting big outs in big spots and they have been really poor in high-leverage positions, but also our offense has been the same way.”

Ross indicated near the end of the Cubs’ 2-7 road trip that right-hander Jeremiah Estrada would be among his high-leverage options going forward. Estrada’s moment came in the sixth inning Tuesday in relief of Drew Smyly, who loaded the bases with nobody out while holding a five-run lead. Estrada’s challenge started by facing Mets slugger Pete Alonso, already with a home run in the game.

Estrada successfully limited the damage. He induced Alonso into a fielder’s choice groundout to third, which scored a run, then got pinch hitter Daniel Vogelbach to fly out and Starling Marte to ground out to end the inning. It was the type of outing that can give Ross confidence to use Estrada more frequently in tough spots.

Estrada attacked the Mets solely with four-seam fastballs in his eight-pitch inning.

“Sometimes I get like, ‘Well, they know the fastball is coming, I feel like I need to mix it up a little bit,’” Estrada said. “But I’ve got guys here who’ve been through it who are like, ‘Bro, just trust yourself and do your thing.’

“I see Pete Alonso’s first swing and it’s super far out ahead and you see what he’s chasing and you’re like, OK, trust your stuff. Yan (Gomes) knows the game. Trust your catcher.”

As the Cubs continue to evaluate up-and-coming relievers in the minors, right-hander Codi Heuer will soon provide the bullpen with added firepower. Heuer (Tommy John surgery) is eligible to come off the 60-day IL on Monday, though he might not be activated immediately. Hoyer noted Heuer’s inconsistency during his rehab outings at Triple-A Iowa, where he has surrendered seven runs, walked six and struck out six in 4⅔ innings.

Hoyer was encouraged by Heuer’s most recent outing Sunday, when he threw a scoreless inning and worked around two walks.

“Obviously he can help us,” Hoyer said. “So once we feel like he could definitely help us up here and it’s the right thing, we’ll bring him up. It’ll be nice to have him and his experience come out of the bullpen.”

Minor-league tidbits

  • One young arm who could get a big-league look in the coming weeks has been promoted to Triple A. Right-hander Daniel Palencia joined Iowa on Tuesday from the development list in Arizona, where he honed his off-speed stuff as he makes the move from starter to reliever. Palencia has been simplifying his pitch mix in the new role, Hoyer said.

“It’s nice to have those kind of arms,” Hoyer said. “We’ll be transitioning some of those guys into the bullpen in the weeks and months to come.”

  • Top prospect Pete Crow-Armstrong returned to Double-A Tennessee’s lineup Tuesday after missing five games because of a skin infection, a source told the Tribune. Crow-Armstrong is hitting .276 with a .322 on-base percentage and .788 OPS in 25 games with the Smokies.
  • Outfield prospect Owen Caissie hasn’t been in the Tennessee lineup since leaving Friday’s game with what a source told the Tribune is hamstring tightness. The Cubs don’t consider it serious.

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