from Amazon
Wednesday, October 08, 2008
The future of your team
winClass n next3 regr3 over500 reg500
0.378 26 0.458 0.451 19% 13%
0.429 157 0.478 0.472 35% 29%
0.476 265 0.489 0.490 45% 43%
0.522 311 0.507 0.509 57% 57%
0.571 144 0.530 0.528 70% 71%
0.617 39 0.572 0.547 95% 85%
From 1969-1971, the Expos had a .404 record. I put them in the “.400-.450” win class. (That’s an average of .429 for all the teams in that class, which is the second line in the chart, under the “winClass” column.) From 1972-1974, they had a .476 win%. That’s a close match to similar teams (actually, .478, under the “next3’ column). Teams in their win class (the .400-.450 win class) ended up with a 3-yr win% of over .500 35% of the time (that’s the “over500” column).
If we regress their win percentage 60% toward the mean, we end up with the reg3 column (that’s win% times .4 plus .3). As we can see, a pretty strong match, except for the really, really good teams. If we take their win%, times 3, minus 1, you get the reg500 column. Again, a decent match.
So, the 2006-08 Pirates, with a win% of .416, is expected from 2009-11 to have a .466 record, with a 25% chance of having at least a .500 record over those three years.