I'm not being a smarta** here but ... what is that?

It's a visual representation of how each event in the baseball game affected the probability that the Phillies would win. As you can see, it starts at .500 (anyone's game). As the Phillies got men on base / scored runs, the meter drifted towards them. With Morse's home run, the meter suddenly turns sharply back towards the Nats, where it remains until the bottom of the ninth, where it sits at around ~5% (i.e. 95% probability that the Nats will win) when Storen steps to the mound. After that it is one long, dizzying slope of improbable events and the Nats lose. The probabilities, by the way, are based on tens of thousands of baseball games and how each situation in those games, in each inning, was related to the probability that the home team won. It is all hard maths and science.