BOSTON -- After the baseball caromed off his glove, Cubs shortstop Dansby Swanson slumped over in the left-field grass in frustration on Sunday night. The fact that he was even in a position to make a catch was a feat of its own, but the long sprint ended with Fenway Park’s lights flashing and the Red Sox celebrating a 5-4 walk-off victory.

“Dansby’s the best shortstop in the game,” Cubs outfielder Mike Tauchman said. “I know he expects himself to make every single play; that’s the standard he holds himself to. But from my point of view, I didn’t even think he was going to get close to it.”

The final play of the Cubs’ series-ending loss in Boston was an example of how small the margin of error is right now for a Chicago team playing amid a pile of injuries. Sunday’s starter, Hayden Wesneski, was a last-minute replacement for injured lefty Jordan Wicks. Two relievers called up from Triple-A Iowa before the game covered three innings.

The Cubs’ current 26-man roster features nine players who began the season with Triple-A Iowa. The injured list currently includes multiple players from the rotation (Justin Steele, Kyle Hendricks and Wicks), the lineup (Cody Bellinger and Seiya Suzuki) and the bullpen (Julian Merryweather and Drew Smyly).

Even with a series loss to the Red Sox, the Cubs have a 17-11 ledger and sit just a half-game back of the National League Central-leading Brewers. Over the offseason and into the spring, the front office felt the depth of the organization was in a strong position for a contending season. That has been put to the test in extreme fashion.

“We’re sort of pushing that depth,” president of baseball operations Jed Hoyer said this weekend. “Having some of the young players come up and contribute, I think, is really valuable. And if they can have some success, I think that’ll carry us a long way throughout this season, because we’re going to need their contributions throughout.”

Hoyer’s comments came before the development with Wicks, who was originally supposed to start Sunday before a left forearm strain landed him on the 15-day IL. That led to Cubs manager Craig Counsell naming Wesneski the replacement starter, even after the righty had logged multiple innings of relief only three games ago.

When Wesneski got the news, his reply to Counsell was succinct.

“He said, ‘My job is to get the first guy out,’” Counsell said. “That, I think, is a good way to say it. It’s not to think about, like, ‘Oh, I’ve got to get five innings or six innings.’ It’s just, ‘Get the first guy out,’ and then move on to the next thing. I think that’s a good way to treat it.

“These are opportunities. This is an opportunity to get better for growth. It’s a challenge.”

Wesneski answered the call with four solid innings, in which he threw 63 pitches. Some fluky plays behind him led to two runs (one earned) for Boston, but Counsell said the righty gave Chicago “exactly what we needed.” Behind Wesneski, Richard Lovelady and Daniel Palencia (each promoted from Triple-A on Sunday) combined for three scoreless frames to help set the foundation for a comeback.

Matt Mervis, who was summoned from Iowa on Tuesday, came through with an RBI single in the seventh. Rookie Pete Crow-Armstrong -- called up Wednesday after Bellinger was shelved with two fractured ribs -- helped spark a rally in the eighth with a leadoff single. Two batters later, Tauchman (playing regularly now to shore up the depleted outfield) tied the game with a three-run blast to center.

“It speaks to the depth that we have,” Bellinger said. “I mean, it doesn’t necessarily surprise me, because I think we all knew how good we were, right? And so I think we’re all just playing good baseball. Obviously, we’ve had some crazy injuries, but the guys that come in have stepped up and have played really well.”

The key is to sustain the good play as long as possible, minimizing the impact of the losses.

Steele is set to make his first Minor League rehab start on Wednesday for Iowa, putting his comeback on the horizon. Suzuki is ramping up his workouts and could be nearing game action in the near future, too. Hendricks threw off a mound on Saturday. Bellinger was feeling optimistic about his timetable after upping his activity on Sunday.

“Injuries do happen,” Wicks said. “Obviously, you don’t want them to happen, but it’s part of the game. And when you have depth like we do, it helps to kind of weather the storm until we can get those guys back.”