Boston Red Sox left-hander Chris Sale will undergo Tommy John surgery on his left elbow, according to Ken Rosenthal of The Athletic.

He will miss the entirety of the 2020 season, whenever it begins.

Sale was previously reported out indefinitely with left elbow inflammation, though–after a series of meetings with Dr. James Andrews–it was thought he would not require surgery.

However, the option to undergo a Tommy John procedure was always on the table. Sale went on the shelf at the end of last season due to the same issue, and he has had elbow problems in each of his last three years with the Red Sox.

Given the regular season remains suspended for an unknown portion of time, Sale might have felt it was more sensible to go under the knife now than to try and ride things out.

Still, this is rather tough news for a Red Sox team that will already be noticeably missing former right fielder Mookie Betts in the lineup after they traded him to the Los Angeles Dodgers. Boston also traded away left-handed starter David Price in that deal, making the loss of Sale that much more crippling.

There are other reasons this news is so discouraging. The Red Sox signed Sale to a five-year, $145 million extension last March, but Sale's 2019 left much to be desired even before he went on the shelf. Sale went 6-11 with a 4.40 ERA in 25 starts, with his walks per nine innings and homers per nine innings both seeing significant increases.

That said, there is no replacing Sale in Boston's rotation this year. The timing of the surgery is also concerning considering he will be 32 next March, and it seems hard to believe he can be the same dynamic strikeout guy he has typically been throughout his career.