Williams, who has suffered with inflammation and confidence issues in the past, had to have both legs in ice after the defeat.
"It's not my highest. It's been tough, just being in and out of the lineups, missing two weeks here and there," the 29-year-old told the New York Post after the game.
"I feel like I get my legs back, get my legs in shape, and then I go out again. Then I've got to just do it all over again. It's just been a struggle.
"I think back-to-backs have been tough the whole year on me. I played a lot of minutes, and I could feel them getting heavy, but there's no excuses. That's my job. I've got to find ways to push through it."
The Nets currently occupy second position in the Atlantic Division with a record of 20-25.