Can someone explain what is this “Expected Win-Loss” (ExWL) stat at the far rightmost column on this site this ESPN site? Take the Orioles, for example. The value in this column almost matches their actual W-L record. So, WTF? It’s like a night by night prediction? Still, I say…WTF? (For other teams, it is not even close…so??? What does that tell me? The pros who make such predictions are better off being weathermen?)
Expected win-loss is based on the formula [Runs Scored][sup]2[/sup]/([Runs Scored][sup]2[/sup]+[Runs allowed][sup]2[/sup]). It’s based on historical observation; the formula has been observed to fairly closely match actual historical results.
It doesn’t really mean much; it’s just a fairly accurate predictor. Baseball fans (and especially baseball analysts) like stats.
The basic gist of it is that if you have a team in June whose W-L record is radically different from their expected W-L record, they are likey to be very lucky or very unlucky, and will probably not continue to play as well (or as badly) as they have been.
At this point in the season, of course, it’s meaningless, because there’s no time left for trends to change.
Well the other thing it can do is show much of a team’s W/L is based on luck (ie, randomness). The Runs Scored vs. Runs Allowed should equal a team’s W/L, but if they over perform or underperform that number it may indicate that they are getting a bit lucky or unlucky.
At this stage in the game, things are almost wrapped up, but earlier in the season it may have indicated which teams may over or under perform their current W/L for the rest of the year (or maybe the team is just strange and wins a lot of blowouts and loses the close games or vice versa).
One of the interesting thing in the current standings is look at Oakland’s ExWL compared to their actual W/L and then look at their record in one run games.
It’s also called “Pythagorean” in some circles.
FWIW, it was popularized in the 90’s/early 2000s (although invented many years earlier by Bill James, I think) as a way to show the true talent of a team by not giving the same weight to a 1-run win and a 10-run win. If you have a bunch of 10 run wins, the theory goes, your team is probably better than its record.
In the last few years, it’s fallen out of favor, not because it’s worse than W/L, but because there are other stats which go even further to try and strip out randomness and sequencing. For example, your team might score a bunch of runs (making your pythagorean look great), but maybe those runs were scored in an unsustainable fashion (like hitting for a high average in clutch situations, having a high BABIP, or having a huge percentage of your fly balls go for home runs).