Williams was optioned to Triple-A Syracuse by the Mets after being acquired in a trade with the Cubs on Friday, Mike Puma of the New York Post reports.
The Mets presumably wanted Williams to bolster their rotation depth, but they don't actually need that depth right now. He'll wait in the minors until called upon, though the news that Jacob deGrom (forearm) suffered a setback Friday could mean Williams is needed sooner rather than later.