The Yankees expect the veteran left-hander to return in three to four months. They open the year March 26 against the Baltimore Orioles.
According to the New York Post's Joel Sherman, Paxton's injury dated back to the regular season:
The team strengthened its starting rotation by signing Gerrit Cole to a record-setting nine-year, $324 million contract. Masahiro Tanaka, Luis Severino and J.A. Happ round out what is still a solid unit. The timing of Paxton's procedure allows the Yankees to use spring training to audition possible replacements.
New York remains the favorite to win the American League East, even with Paxton out for the first few months.
The Baltimore Orioles and Toronto Blue Jays are outsiders, and the Boston Red Sox appear to be waving the white flag for 2020 after trading Mookie Betts to the Los Angeles Dodgers in a three-team deal reported by ESPN's Jeff Passan. That leaves the 96-win Tampa Bay Rays, who can't match the depth available to the Yankees.
The back surgery is poorly timed for Paxton, who's set to become a free agent next offseason.
When healthy, the 31-year-old is one of the better starters in baseball, having averaged nearly 11 strikeouts per nine innings over his career.
However, Paxton has never thrown more than 160.1 innings over a season. The Yankees also placed him on the injured list with left knee inflammation last May.
No matter how good he performs upon returning to the mound, many teams will likely question Paxton's durability when the time comes to weigh contract offers.