Wong wasn't that far off the bag. What did happen is that he made a little hop trying to get back to first - and his feet slid out a little under him.
there was one of those sport science videos that shows in pressure playoffs situations your muscles tense up 13% more than usual, this might have happened to wong and resulted in the slip.
Yes, there's what Doc Larry says. But there's also brain cramping due to the pressure. He shouldn't have even put himself in a situation where a small slip causes him to be picked off. They're down by two in the ninth, and he's the first run. The marginal benefit of that extra step or two in his lead is pretty close to zero.
To be fair, though, that's one the first base coach as well as Wong.