When Home xGD is less than -1.0 the home team wins just 21 percent of the time. When the xGD is greater than 2.0 the home team wins 78 percent of the time. Interestingly, the probability of drawing does not change much across the outcomes. Draws range between a 16 percent chance and 31 percent.

Let’s use the Nashville example to dig further. According to the ASA model, Nashville tallied 0.73 xG while Atlanta mustered just 0.27 xG, a difference of 0.46. That the home team “won” xGD by between 0.25 and 0.50 points happens 12% of the time. That’s roughly the median result for nine seasons in the analysis. Teams that pull that off win the game 51 percent of the time and draw 31 percent of the time, so the fact that they lost happens just one in five times. It is worth mulling that even a separation of half a goal in terms of xG only earns a team a coin flip when it comes to winning. Soccer just has a way of being unpredictable.

Mr. McKinley’s consolation to Nashville fans appears to be justified. Nashville performed roughly average at home against one of the East’s historically best sides, and while they lost, it’s a situation they will win half the time. Expected goals do tell an interesting story after a match. Now we just have to wait a half dozen more games to find out how good Nashville should expect to be.