Mets' pitcher Walker disengages before a time-out is granted, leading to a 10th inning walk-off balk.

Sure. Bottom of the 10th with bases loaded for the Royals. They were playing at home, so they are on offense for the second part of the inning meaning they win instantly if they break the tie.

The batter has to be set and facing the pitcher when the timer reaches 8 seconds and then the pitcher has to throw the pitch before the timer runs out. But there is also a disengagement rule: once a pitcher is set, he cannot leave the rubber unless he throws home of attempts a pickoff. If he does disengage it will be called a balk and all runners will be awarded an extra base.

In this case there was an issue with the pitch com. The pitcher shortly lifts his leg to step off, probably thinking a timeout was already granted, but it wasn't. And at that point that counts as a balk.