Hicks originally hurt his elbow in August and missed two months of action before returning for the Yankees' ALCS loss to the Houston Astros. He previously told reporters he did not expect to have Tommy John surgery, but an examination after the Yankees' postseason elimination determined it was necessary.
The Yankees were without shortstop Didi Gregorius for the first half of the 2019 season after he underwent Tommy John surgery last October. Gregorius returned to the lineup in June, putting him in the eight-month recovery window.
Hicks signed a six-year contract extension with the Yankees earlier this year that will keep him with the club through at least 2025. The Yankees should have enough lineup depth to survive without Hicks for most of next season, and they're expected to be major players in the free-agent pitching market after having rotation issues throughout 2019.
Hicks is very clearly part of their long-term plans, so don't be surprised if they are cautious with his recovery time.