Yankees don’t have to look far for Gregorius’ worst-case scenario

Didi GregoriusDidi Gregorius could potentially return from Tommy John surgery by the middle of next season, which the Yankees would no doubt sign up for.

All they have to do is look across town for a worse alternative.

Mets utilityman T.J. Rivera underwent the same procedure on his right elbow in September 2017, with hopes of being back with the team during the latter part of this past season.

Instead, his minor league rehab stint ended in July after just six games, and he was shut down for the rest of the season.

Rivera, 29, said he expects to resume a throwing program soon and is confident he’ll be fine for spring training, but he’s also learned not to predict anything when it comes to the…