text:  Arnon Mishkin is the director of the Fox News decision desk. The Donald Trump that walks in that debate and how he performs tonight is subject to a lot of speculation. And nobody really knows, frankly, other than him. And my own sense is that he's an exceedingly shrewd player. He knows exactly when to sort of belt it out the way he can do at rallies. And at the same time, he knows when to play it soft and be sort of very presidential.