Hello, and welcome to Phil Birnbaum’s take on Bill James Online.
In the study called “Curses” (subscription required), Bill figures out that the chance of a team winning the World Series is almost exactly proportional to the cube of the difference between its wins minus its losses. So if the Yankees go 100-62 (38 games over .500), while the Red Sox go 97-65 (32 games over .500), New York has almost a 50% higher chance to win the World Series than Boston does.
Of course, that doesn’t mean *in the same season*. Obviously, if the Yankees and Red Sox had those records in the old two-division AL, the Red Sox would have *zero* chance. Rather, what it means is that if those teams had those records in two separate seasons, the Yankees would be 50% likelier to win their WS than the Red Sox would be to win theirs.
Bill nonetheless uses this method to figure the chances in the same season. He lists all the teams with winning records from 2003, and gives them “claim points” based on the cubes of their games over .500. The Yankees were 40 games over, so get 64,000 points. The Blue Jays were 10 games over, and get 1,000 points. Therefore, the Yankees have 64 times the chance the Blue Jays have.
The sum of all the teams’ cubes is 272,767. So the Yankees chances of winning the WS are 64,000 divided by 272,767, which is 23%. The Blue Jays are 1/64 of this, at an 0.4% chance.