That is pretty much like saying, ‘Man, our team really tore it up in preseason.’
His performance only mattered in the big game.
I am trying to grasp your thinking here. Your implication is that if Moore had just gave a better "performance" that would have caused him to win the "big game."
Why this is so difficult for me is because I see no correlation whatsoever to Moore's performance and his losing 20 percentage points in the polls. Moore did not act radically different than he has always acted, and in the absence of accusations was predicted to win quite handily.
Therefore it seems to me that "performance" has got nothing to do with it, and so how it is analogous to a "big game" I fail to see.
A closer analogy would be someone coming out of the stands and smashing the quarterback's knee with a baseball bat while his own teams cheerleaders cheered them on.
In this case too, "performance" isn't going to win.