PHOENIX -- It wasn’t the decision D-backs manager Torey Lovullo wanted to deliver. It wasn’t the news Jordan Montgomery wanted to hear. It wasn’t how Arizona envisioned using its $25 million starting pitcher in the dog days of summer when he was signed two days before Opening Day.

Ultimately, with the club pursuing its second straight playoff appearance, moving Montgomery to the bullpen was a business and baseball decision. If the club wants to reach the same heights as playing in the World Series, its best arms need to be starting the game.

"He didn't like it. I didn't want him to like it, nor did I expect him to like it,” Lovullo said before the D-backs' 8-3 loss to the Mets on Tuesday night at Chase Field. "I think he knows for the good of the team, getting into this role and figuring out this role as quickly as possible is going to be the best situation for this team, and that ultimately is what I needed."

As tough as hearing the news was for the veteran left-hander this past weekend, that same day he started studying the art of being a reliever by asking questions to his teammates and coaches.

All that advice came in handy on Tuesday as Montgomery made his relief debut against the playoff-contending Mets, pitching 4 1/3 innings in relief of Brandon Pfaadt, allowing no earned runs on five hits and just two walks. It didn't help the D-backs as their six-game winning streak came to a close, but it’s one step toward Montgomery regaining his confidence -- which he said has been the “main issue” for his struggles this season.

"I want to help the team any way I can,” Montgomery said. “We're in a pennant race, and if I can be the long man and maybe turn myself into a leverage arm, get us some big outs and be a difference maker that way, then that's just what I'll do this year."

As Pfaadt exited the game in the fifth inning with runners on second and third and two outs, Montgomery jogged in from the bullpen with his warm-up song “Back Down” by 50 Cent playing throughout the stadium soundsystem.

It was beyond unfamiliar territory for the 31-year-old southpaw, whose last appearance out of the bullpen was Sept. 15, 2019, with the Yankees.

To wit: Montgomery said that his pregame routine usually takes about 40 minutes to complete. He only had six minutes before entering the game on Tuesday.

It wasn’t an ideal start as the Mets scored three runs, Montgomery allowing three baserunners on a hit-by-pitch, a walk and an error from shortstop Geraldo Perdomo, but he got out of the jam by striking out Francisco Lindor. Montgomery settled down the rest of the way, stranding the five runners he allowed after his first inning in the fifth and getting Pete Alonso, who homered off Pfaadt in the second inning, to strike out with a runner in scoring position.

"He did his job the way we wanted him to do his job,” Lovullo said. “I was really happy for him. Very proud of him for making the adjustment and figuring it out. He's only pitched out of the bullpen once. That's a huge adjustment for somebody that takes 28 to 32 minutes to get ready for his first pitch, he did in six and a half minutes."

Even with Montgomery’s experience, adjusting on the fly like this was still a tough challenge. That’s why Lovullo made it a point to praise him for adapting to the new role so quickly, giving the D-backs a long reliever.

But the skipper didn’t rule out a return to the rotation for Montgomery if the pieces fall into place.

"Anything could happen,” Lovullo said. “I'm going to be paying attention to everybody's performance. … This is a competitive game. At this point in time in the year, the best players are going to get the most reps, and I want him to continue to do what he did today.”

The D-backs know Montgomery can become that pitcher. In 2023, he set career highs in ERA (3.20), strikeouts (166) and innings (188 2/3) over 32 starts between the Cardinals and Rangers, earning his first World Series title at Chase Field with Texas.

For now, he’ll be willing to help the D-backs be on the celebratory end this season, regardless of what role he has.

"Baseball is weird,” Montgomery said. “You never know what could happen. I’m just going to stay ready and keep working hard every day."