Yankees claiming Jacoby Ellsbury went behind their backs in grievance

The Yankees are expected to officially file a grievance against Jacoby Ellsbury on Friday, once Ellsbury clears release waivers, with the intent of converting Ellsbury’s contract from guaranteed to non-guaranteed, multiple industry sources told The Post.

The basis of the grievance is that Ellsbury, who missed the entire 2018 and 2019 seasons due to multiple injuries, received medical treatment without the Yankees’ authorization for multiple years.

Ellsbury, released by the Yankees on Wednesday, is due $21 million for 2020 as well as a $5 million buyout of a $21 million team option for 2021. It’s possible the Yankees could attempt to recoup some of the $127 million they already have paid him.

If a grievance can’t be settled between the two sides, then it goes to an independent arbitrator for resolution.

The case brings to mind Carlos Beltran’s dispute with the Mets in 2010, when Beltran underwent surgery on his right knee. The Mets contended that Beltran, represented by Scott Boras at that time, did so without the team’s consent. Ultimately, the team backed down on its threats to litigate.

Boras now serves as Ellsbury’s agent as he is shopping stud free agents like pitchers Gerrit Cole and Stephen Strasburg that could help the Yankees next season. While both the Yankees and Boras are experienced enough to multi-task, the grievance certainly throws a compelling ingredient into the dynamics.