PHOENIX -- A primary reason for the D-backs’ recent success has been their ability to win close games. They’re tied for second in MLB with eight wins by one run, a marked improvement from 2021, when they went 10-31 in such contests.

With Saturday’s game against the Cubs tied heading to the ninth inning at Chase Field, the D-backs had another opportunity to earn a close victory. That didn’t happen this time, though, as Chicago tagged closer Mark Melancon for three runs and gave Arizona a 4-2 loss.

• Box score

Here are three key takeaways from the night:

1. 'Zac Gallen Day' is becoming a must-watch event
Madison Bumgarner may be Arizona’s most proven starting pitcher, but Zac Gallen is becoming the rotation’s clear ace. The right-hander tossed six dominant innings of one-run ball vs. the Cubs, putting his ERA at 1.05, which is tied with the Marlins’ Pablo López for the best in MLB.

Gallen struck out a season-high nine while yielding only one run, which came on one of the two hits he allowed -- a homer by Yan Gomes in the fourth inning. That was the first home run given up this season by Gallen, who has allowed only four runs in 34 1/3 innings.

Every time Gallen takes the mound, he’s giving his team confidence it will have a great chance to win that day.

“How he goes about it, just the look -- he has all of that,” D-backs bench coach Jeff Banister said. “There’s a lot of precision to [his stuff]. There’s a lot of swagger, a lot of confidence with it. That just helps everybody around you.”

Banister sees similarities between Gallen and former All-Star hurler Cole Hamels, whom Banister managed in Texas from 2015-18. Gallen also does a lot of research between starts, and he’s seeing the results after a tough ‘21, when he had a 4.30 ERA while dealing with several injuries.

“I feel like I’m in a good rhythm. Being able to be healthy and put some decent work in every day has really helped me out a lot,” Gallen said. “The stuff I’m working on and the adjustments I’ve felt like I’ve needed to make have worked out.”

2. Thomas is proving to be the real deal in his first week
There’s been a lot of hype surrounding Alek Thomas, MLB Pipeline’s No. 18 overall prospect who made his big league debut last Sunday. And through his first seven days in the Majors, the 22-year-old outfielder is living up to it.

After batting in either the eighth or ninth hole in each of his first four starts, Thomas moved up to the No. 7 spot on Saturday, and he had his third multi-hit game of the week. He singled in the fourth, doubled in the sixth and drew a leadoff walk in the ninth before scoring on a Daulton Varsho single.

Thomas has a long career ahead of him, but it’s been an encouraging start, given that some top prospects struggle when first making the big jump to the Majors. He’s playing strong defense in center field, and he’s utilizing his plus speed, such as when he forced an errant pickoff throw in the fourth on Saturday and moved up to second base.

If Thomas keeps playing at this level, it may not be long before he starts moving even further up the D-backs’ order.

3. Melancon’s strong April is being followed by an inconsistent May
Melancon was among the D-backs’ most notable signings this past offseason, as the 37-year-old right-hander was brought in to stabilize the back end of the bullpen. That’s what he did in April, when he posted a 1.13 ERA in eight games.

On Saturday, Melancon allowed two hits and two walks without recording an out. He now has a 24.55 ERA through his first six outings of May, having allowed three or more runs three times and falling to 0-5.

“The bottom line is he’s got to execute at a higher level, no matter what, if it’s a tied game or not,” said Arizona manager Torey Lovullo, who added that the closer needs to have better command of his cutter.

Most of Melancon’s troubles have come in non-save situations. He’s converted seven of eight save chances, while allowing 10 runs (eight earned) in 4 2/3 innings over his six non-save opportunities.

“This is unusual and not to go on any longer, for sure,” Melancon said. “I can’t say the situation is a factor. It’s ironic. But this is my job in a tied situation, and I need to take care of it.”