PEORIA, Ariz. -- The Padres on Thursday bolstered the team's once-thin starting rotation by signing veteran right-hander Michael Wacha to a one-year deal with player options for 2024, '25 and '26. The agreement also includes a two-year club option for the 2024 and '25 seasons.

The deal guarantees Wacha $26 million over four years, a source told MLB.com's Mark Feinsand, and here's how the deal is structured:

Signing bonus: $3.5 million
2023: $4 million

Club options, must be picked up simultaneously:
2024: $16 million
2025: $16 million

If club options are declined (all one at a time):
2024 player option: $6.5 million
2025 player option: $6 million
2026 player option: $6 million

For 2023 and any player options (but not club options):
$500,000 each for 20, 25 games started
$1 million for 30 games started

Wacha, 31, is coming off a season in which he posted a 3.32 ERA in 23 starts for the Red Sox. He'll be entering his 11th big league season with his fifth team, but he spent the bulk of his career pitching in St. Louis -- seven seasons where he reached the postseason three times and took home 2013 NLCS MVP honors. 

In St. Louis, Wacha posted a 3.91 ERA from 2013-19, before regressing in the ’20 and ’21 seasons. He notched a 6.62 mark with the Mets in ’20, then a 5.05 ERA with the Rays in ’21. But Wacha’s bounce-back season in Boston made him a solid candidate to bolster the Padres' rotation. By the time he agreed with San Diego, he was the market’s top remaining free-agent pitcher.

Wacha slots into a starting rotation that already features Yu Darvish, Joe Musgrove and Blake Snell at the top. Right-handers Nick Martinez and Seth Lugo -- both of whom have a track record of success in the bullpen -- are set to slide into starting roles to start the season as well.

So the Padres were set to open camp with five starters. But they had espoused their desire for a six-man rotation, citing that plan's effectiveness in the early stages of 2022. Perhaps they'd pare down to five later in the year, but they wanted to open the season with six, easing the burden on the entire staff.

“Taking advantage of that extra day, it seemed like all of our guys were on it,” manager Bob Melvin said. “… We rely on our starters. They were fresh at the end of the year. A lot of things popped up because of this. If we were able to do it, I wouldn’t put it past us doing it again.”

But -- as Melvin pointed out last week -- the Padres would need six capable starters to do so.

They appear to have found their missing piece in Wacha, whose arrival just might signify the final move in the team’s offseason roster construction. (Never, ever put it past general manager A.J. Preller to make further transactions, but team officials feel relatively content with the depth that’s been created.)

For one, Wacha’s arrival eases the burden significantly on Lugo and Martinez. No longer is that duo being quite so relied upon to transition seamlessly into the rotation. Meanwhile, 23-year-old lefty Adrian Morejon might now be destined for a swing-man role or to be a multi-inning weapon out of the bullpen.

On top of that, the organizational pitching depth gets a significant boost with the Wacha signing. Previously, a handful of Minor League options were set to compete for that No. 6 starter job in camp. Had nobody won it, the Padres would’ve settled for a five-man staff.

Instead, that group of Minor League pitchers – including Jay Groome, Reiss Knehr, Ryan Weathers, Pedro Avila, Julio Teheran and Wilmer Font – will serve as invaluable depth pieces and stability in the event of injury.

The Padres, of course, have big goals for the 2023 season. They’re coming off their first trip to the NLCS in 24 years, while welcoming Xander Bogaerts into the fold and eventually welcoming back Fernando Tatis Jr. It’s a star-studded roster. But they wanted to ensure it was a complete roster, too.

The addition of Wacha should go a long way toward ensuring that it is.