The Red Sox added a proven starting pitcher who can bolster them for the 2022 stretch run and perhaps beyond, signing lefty James Paxton to a one-year deal that includes a two-year club option for the ‘23 and ’24 seasons. The club did not announce financial terms, but a source told MLB.com the deal is worth $10 million.

Paxton, a lefty, had Tommy John surgery in April and likely won’t pitch for Boston until midseason at the earliest.

If the options are picked up, the deal could wind up being worth close to $35 million.

“We do expect to see him sometime in the second half of the season if all goes well,” said Red Sox chief baseball officer Chaim Bloom. “We're hopeful that when he does come back, he's going to be able to give us a lift.”

Chad Dey of SportsNet in Canada and ESPN’s Jeff Passan were first to report the agreement, which is pending a physical.

Paxton made one start for the Mariners in 2021, allowing one run in 1 1/3 innings before leaving the game with elbow discomfort. Soon thereafter, the decision was made for him to have Tommy John surgery.

The 33-year-old spent his previous two seasons with the Yankees, including a 2019 season in which he went 15-6 with a 3.82 ERA. Paxton went 41-26 with a 3.42 ERA over the first six years of his career with Seattle, including a no-hitter on May 18, 2018, in his home country of Canada against the Blue Jays.

In 2017, Paxton came into his own for the Mariners, going 12-5 with a 2.98 ERA in 24 starts.

From 2017-19, Paxton was one of the best lefty starters in the game, posting a 38-17 record with a 3.54 ERA, holding opponents to a .230 average while striking out 550 over 447 innings.

“We've seen before injuries really started to impact his career, he was one of the better left-handed pitchers in the American League,” Bloom said. “And, if he gets back to that, he could provide a huge boost for us in the second half.

“And we also have the ability, if all goes well coming here, to control him for a couple years after that. That was a big part of this deal for us -- adding someone who might be able to help us down the stretch this coming year but then also be a big part of what we're doing in the years ahead.”

Once Paxton returns from his rehab, he will join a Boston rotation that includes Chris Sale, Nathan Eovaldi, Nick Pivetta and the recently-acquired Michael Wacha.