PHOENIX -- The D-backs’ 3-2 loss to the Cubs on Sunday afternoon at Chase Field ended a streak. Arizona had won three consecutive series and had either won or split each of its previous five, before dropping two of three games this weekend.

Still, there continues to be a lot of optimism surrounding the D-backs a little more than a month into the 2022 season. And for good reason. After losing 110 games last year, Arizona comes out of this 5-4 homestand with an 18-17 record -- plus, plenty of those losses have been close enough that one swing could have pushed them the other way.

“We’ve almost won a lot of ballgames; we’ve been in a lot of them,” catcher Daulton Varsho said. “It’s been a lot of fun to be around this group. It’s a young group, and it’s been a lot of fun -- a lot of energy, so it’s been exciting.”

The series finale on Sunday marked the second day in a row the D-backs and Cubs were tied heading to the ninth inning. On Saturday, Chicago rallied for three runs off Mark Melancon to win. This time, Frank Schwindel’s RBI single off Arizona right-hander Ian Kennedy was the decisive swing.

The D-backs opened the bottom of the ninth with back-to-back singles from Christian Walker and Pavin Smith, but Varsho popped out in foul territory and David Peralta hit into a game-ending double play.

“I always believe that somebody’s going to come up and get a big hit in a big situation,” manager Torey Lovullo said.

That hasn’t always been the case this year for Arizona, though, which is batting a National League-low .204 through its first 35 games. The biggest reason the D-backs have won more than they’ve lost has been their starting rotation.

Humberto Castellanos allowed a run in each of the first two innings vs. the Cubs on Sunday, but he settled in nicely after that. He struck out five over 5 1/3 solid innings, not yielding any more runs after the early pair.

After recording a 5.79 ERA over five games (three starts) in April, Castellanos owns a 2.76 ERA in three May outings.

“He’s doing exactly what you want a fifth starter to do,” Lovullo said. “You want him to be able to give you a chance to win a baseball game every fifth day, pitch deep enough into the game that you’re not going to have to burn up your bullpen. He’s been fantastic for us.”

So have the D-backs’ other four starters (Madison Bumgarner, Zac Gallen, Merrill Kelly and Zach Davies). Arizona ranks second in MLB with a 2.51 rotation ERA. And when Castellanos takes the mound, he wants to do his part to keep that number low.

“It’s a big responsibility, it’s something that I have to continue as well,” Castellanos said through an interpreter. “My teammates have been doing a great job in the rotation.”

The only team with a better rotation ERA than the D-backs? The Dodgers (2.45). And on Monday, the NL West rivals open a series that will feature four games in three days in Los Angeles.

When the two teams met for the first time this season, Arizona took two of three games at Chase Field from April 25-27. But it’s always a tough task to take on the Dodgers, who currently sit atop the division at 21-12.

“It’ll be a good test for us,” Lovullo said. “But every day’s a test. Every day, we’ve got to come out and bring it.”

So far, that’s what the D-backs are doing. It has led to better showings on the field, even in games they’ve come up short.

“It’s fun to be in tight games. It’s better to be in those than blowouts,” Varsho said. “We’re just not finishing them right now.”

But the D-backs are also confident they will soon. And if they continue to pitch this well and the offense starts to pick up, there’s reason to believe them.