CHICAGO -- Winning a baseball game is rarely easy, and it’s usually a collective effort of pitching, defense, and timely hitting. Sometimes losing a game is a collective effort of these things, too.

The Cubs’ 7-6 loss to the D-backs can mostly be attributed to a rare lapse for the bullpen. The group had been reliable all season leading up to taking over on Saturday for starter Justin Steele, who tossed five shutout innings. Cubs relievers had allowed just six earned runs in their last nine games, from May 11-20, and had posted a 1.69 ERA in their last 32 innings pitched.

Not all of the runs the bullpen gave up against the D-backs were earned, though. Defensive mistakes contributed to the seven Arizona runners who crossed the plate after the fifth inning. Ildemargo Vargas misplayed a ball off of Ketel Marte’s bat in the eighth inning -- the initial scoring was an error but it was later changed to a single -- which eventually lead to Marte scoring and the D-backs tying the game on back-to-back hits by Jake McCarthy and Daulton Varsho.

Arizona took a three-run lead in the tenth inning, thanks to both the wobbly bullpen and the shaky defense. One batter after taking a liner off of his right forearm, Rowan Wick gave up the go-ahead hits, including a Varsho double that ended with him advancing to third and then scoring on a poor throw by Andrelton Simmons.

Before Wick got the ball, two Cubs relievers who had been nearly untouchable looked a little more human. Scott Effross gave up his first home run of the season to pinch-hitter Pavin Smith in the eighth inning, which brought the D-backs within two runs. Going into Saturday, Effross had not allowed an earned run since April 17 against the Rockies. Making his third appearance of the season, Brandon Hughes allowed one run on three hits. In his first two games, Hughes had not allowed a hit in 3 1/3 innings pitched.

“At some point, you’re not going to pitch as well as we have been pitching,” manager David Ross said. “We were behind a couple of hitters at times. These guys took a lot of borderline pitches to their credit, and then we’ve got to make plays behind them as well.”

The defense is a factor that cannot always be controlled by the manager; Vargas and Simmons are both in the lineup because Nick Madrigal and Nico Hoerner are on the injured list. Similarly, a poor showing by the bullpen can’t always be predicted. Given how his starter had been pitching, Ross might have been tempted to leave Steele in for another inning.

Through five, Steele had struck out nine D-backs -- three of them looking -- and had only allowed three baserunners. But at 89 pitches, Ross was mindful of how much he wanted to test a young arm.

“I don’t think he was as efficient as he would like to be,” Ross said. “I mean, 90 pitches through five. I think that’s close to as far as we have given him. I don’t know that I was that tempted the way our bullpen’s been throwing the ball, and I thought he had to work kind of hard in his early innings. Sometimes those can bite you on the back end.”

Though Ross said he was being careful to keep Steele under 100 pitches, his greater concern is that he is not running his pitcher back out on the mound after a tough inning. Steele was racking up strikeouts early on, but it was taking him a lot of pitches.

“There was a point in time [...] when my fastball command was kind of wavering a little bit, but I was able to make an adjustment and get back in the zone with it,” Steele said.

Even with his pitch count climbing, Steele said he was feeling comfortable with going deeper into the game.

“If [Ross] would have told me to keep going, I definitely would have kept going,” Steele said. “But I was completely OK with his decision to pull me as well.

“Our bullpen has been absolutely fantastic this year, so I completely understand it.”

Before Saturday, Cubs relievers had the third-lowest ERA in baseball (3.10) and the second-highest strikeout rate (28.9%), so their performance against the D-backs was most likely an anomaly.

Offensively, the Cubs’ game plan against Arizona starter Madison Bumgarner was effective. At first. Frank Schwindel said they knew that most of the damage they could do against Bumgarner would come on the pull side. When he and Patrick Wisdom hit back-to-back home runs in the second inning, and hits by Seiya Suzuki and Yan Gomes tacked on two more runs in the third, their game plan appeared to be working. But Bumgarner adjusted and went on to go seven innings, shutting down any further Cubs scoring after the third inning.

A late rally against Arizona’s bullpen in the tenth brought the Cubs back within a run, but Suzuki struck out with Jonathan Villar on second base.