Allan Lichtman seems to be onto something when looking at several races. I'm not sure closing arguments matter at all.

[TwilightZone]

1. Romney made some serious errors toward the end of his campaign

47% being the obvious one, binders full of women, and so on.

Momentum was shifting toward Obama at the end, so a shift vs. the polls is not as unlikely as it might appear.

Those kinds of shifts were never likely in this cycle because Trump's support is historically stable, if also historically low. His approval ratings haven't moved much at all in months, contrary to what one would guess, considering the onslaught of negative press.

Those who were going to be swayed on Trump were swayed long ago. At this point, I think it's more about whether or not likely voters actually show up. The closing arguments could indeed make an impact there, though perhaps not a significant one.