Yankees manager Aaron Boone said he is "optimistic he'll be back at some point during the season … a realistic chance he plays bulk of season."
General manager Brian Cashman said Gregorius had a partial elbow tear that was "asymptomatic" when he was acquired from the Arizona Diamondbacks in December 2014 to be Derek Jeter's replacement at shortstop. Cashman described the current tear as "the finishing part of something that was a sleeping giant, I guess."
Cashman declined to give a time frame for Gregorius' return, saying "best to stay general."
Boone said he thinks Gregorius hurt his right elbow early in an American League Division Series game at Fenway Park, when he retrieved a ball off the wall in left field and threw it in.
He said Gregorius felt something then but played through the final games of the series, which the Boston Red Sox won 3-1.
Boone said Gleyber Torres could be the Yankees' shortstop to begin the 2019 season.
Gregorius batted .268 with 27 home runs and 86 RBIs this season as a big left-handed bat in a lineup heavy with right-handers. He will be entering the final year of his contract in 2019.