PHOENIX -- As expected, Diamondbacks left-hander Jordan Montgomery exercised his player option for the 2025 season, according to baseball sources. The club has not confirmed the news.

Montgomery was a free agent following the 2023 season and remained unsigned throughout Spring Training before the Diamondbacks signed him to a one-year, $25 million deal with a vesting player option the day after the regular season opened.

The 2025 player option vested for $20 million after Montgomery made 10 starts, and it increased to $22.5 million after the veteran made his 18th start of the year.

When Montgomery initially signed the deal, it seemed like a steal for Arizona, which was able to add another quality arm to its rotation. Scott Boras was Montgomery's agent at the time, and the thinking was that with Montgomery not getting the long-term contract value he initially wanted, he would rebuild his value with the Diamondbacks and then go back into the free-agent market.

Things, however, did not go to plan as Montgomery struggled mightily during the season and switched agents.

After compiling a 136 ERA+ while making a combined 32 starts for the Cardinals and Rangers in 2023, Montgomery made 21 starts for the Diamondbacks before losing his spot in the rotation. His ERA+ with Arizona was 67.

As the season wore on, Montgomery became more and more frustrated with his performances.

“I just expect a lot out of myself,” Montgomery said after a June start. “I know I've let a lot of my teammates down and I'm just trying to be better.”

After trying throughout the year to get the left-hander back on track, manager Torey Lovullo removed him from the rotation in late-August.

Following the regular season, Arizona managing general partner Ken Kendrick appeared on Arizona Sports 98.7 FM and took responsibility for the decision to sign Montgomery.

"If anyone wants to blame anyone for Jordan Montgomery being a Diamondback, you're talking to the guy that should be blamed," Kendrick said. "Because I brought it to [the front office's] attention. I pushed for it."

Diamondbacks general manager Mike Hazen later said that while he appreciated Kendrick taking responsibility, the ultimate decision to sign Montgomery rested with the GM.

"That was a group process, and I understand why we made that decision at the time, and I believe that Jordan Montgomery will have a better year next year," Hazen said. "It didn't work out, but I also think next year is going to look a lot different."

The Diamondbacks hope it will, because Montgomery exercising his option means the team now has less room to add to its payroll this offseason.

If Montgomery is able to get back to 2023 form, it would seemingly give Arizona a very formidable rotation.

Along with Montgomery, the rotation will include veterans Zac Gallen, Merrill Kelly and Eduardo Rodriguez. Younger pitchers like Brandon Pfaadt and Ryne Nelson also established themselves in the big leagues this year, and the team has another wave of younger pitchers to provide competition and depth.