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Mo Williams had surgery on his left knee Wednesday in New York.

(Mo Williams' Instagram)

INDEPENDENCE, Ohio -- Mo Williams underwent surgery on his sore left knee Wednesday in New York.

Why does this matter to the Cavs? Because he's still on their roster.

Though Williams informed Cleveland on Sept. 26, the day players were due in Independence for the start of training camp, that he would not return to the team this season, he didn't file retirement papers with the NBA.

That Williams never formally retired was expected -- had he filed those papers, he'd get nothing of the $2.2 million left on his contract. But having surgery while still under contract with the Cavs thickens the plot a bit.

The Cavs would still prefer, and are pursuing, a buyout of Williams' contract for less than the full amount. They could also try to trade him, but, when Williams posted to both Twitter and Instagram Wednesday that he was having surgery, 29 other teams have more reason to steer clear of him.

If another team takes him, they'd have to pay him because he apparently isn't going to formally retire. And he'll be 34 in December. With a surgically repaired knee.

As long as Williams stays on the Cavs' roster, the team can keep only 14 other players. That's why cleveland.com reported Sunday that Jordan McRae, DeAndre Liggins, Dahntay Jones, and Toney Douglas are believed to be competing for the final two roster spots.

The math: if, as assumed, J.R. Smith signs a new contract with Cleveland, and buyout negotiations with Williams stretches past Oct. 25, when the season starts, the Cavs would have two spots to fill.

Williams' surgery was performed in New York by Dr. David W. Altchek, who operated on Kevin Love's shoulder in 2015. Cavs team doctor, Dr. Richard Parker, was consulted on the surgery and will also be kept in the loop on Williams' rehabilitation.

Williams received multiple medical opinions on his knee last season, including from renowned surgeon Dr. James Andrews, but surgery was not recommended. He was diagnosed with chondromalacia patellae, or inflammation of the cartilage under the kneecap, and played sparingly during the second half of the season.

Williams said he's had a sore knee dating back years.

He seemed to take a shot at the Cavs on Instagram Wednesday when he wrote: "Nobody and I repeat nobody actually gave a damn about my health but me. Taking control of my own career/life."

Williams was said to be strongly considering retirement for most of the summer, and then a few days before camp was to start announced on Twitter he was returning for another season.