Postseason Odds, PECOTA version

Last update: Tue May 13 07:46:00 2008 PT



Playing the rest of the season a million times

with some help from PECOTA

by Clay Davenport

See the original version of this report, based entirely on real data (no projections). And the ELO version of this report, based on an ELO rating scheme.

Generated Tue May 13 07:24:56 EDT 2008


Average wins by position in AL East:  99.5 92.3 85.7 76.2 65.6
AL East           W    L    Pct3  Avg W  Avg L  Champions  Wild Card   Playoffs
Red Sox           24   17   .562   92.8   69.2   35.86887   25.40503   61.27391
Rays              22   16   .543   89.3   72.7   20.89680   21.94531   42.84211
Orioles           19   19   .407   67.7   94.3     .15451     .33238     .48689
Yankees           19   20   .599   93.8   68.2   41.86764   24.42871   66.29636
Blue Jays         18   22   .481   75.7   86.3    1.21218    2.47263    3.68480

Average wins by position in AL Central:  94.5 86.4 79.7 73.7 66.3
AL Central        W    L    Pct3  Avg W  Avg L  Champions  Wild Card   Playoffs
Twins             20   17   .451   75.2   86.8    4.10631    1.40415    5.51045
Indians           19   19   .568   90.6   71.4   54.77373    6.25706   61.03079
White Sox         18   19   .475   76.8   85.2    5.71098    2.02088    7.73185
Royals            16   21   .444   71.0   91.0    1.63194     .55362    2.18557
Tigers            16   22   .562   87.0   75.0   33.77704    7.54403   41.32107

Average wins by position in AL west:  91.4 82.8 74.9 66.8
AL West           W    L    Pct3  Avg W  Avg L  Champions  Wild Card   Playoffs
Athletics         23   16   .494   83.7   78.3   32.72101    3.67809   36.39910
Angels            23   17   .537   88.1   73.9   59.11877    2.97714   62.09591
Rangers           19   21   .451   73.3   88.7    5.18438     .64022    5.82460
Mariners          15   25   .463   70.8   91.2    2.97584     .34075    3.31659

Average wins by AL Wild Card:  93.3

Average wins by position in NL East:  96.7 88.7 82.3 75.5 67.4
NL East           W    L    Pct3  Avg W  Avg L  Champions  Wild Card   Playoffs
Marlins           23   15   .438   75.9   86.1    3.09918    2.50788    5.60707
Phillies          21   18   .531   86.7   75.3   23.23357   14.03472   37.26828
Mets              19   17   .580   93.0   69.0   56.40335   12.34390   68.74725
Braves            19   18   .525   84.5   77.5   16.53956   11.15570   27.69526
Nationals         16   23   .444   70.5   91.5     .72434     .66044    1.38478

Average wins by position in NL Central:  97.1 88.8 83.0 78.3 73.5 67.2
NL Central        W    L    Pct3  Avg W  Avg L  Champions  Wild Card   Playoffs
Cubs              23   15   .562   94.3   67.7   63.06514   11.43017   74.49532
Cardinals         23   17   .463   78.9   83.1    4.69069    4.86531    9.55600
Astros            22   17   .444   76.4   85.6    3.13349    2.84952    5.98301
Brewers           19   19   .543   87.6   74.4   24.27942   16.75674   41.03616
Pirates           18   20   .451   73.6   88.4    1.65273    1.56686    3.21958
Reds              16   23   .494   77.0   85.0    3.17854    3.26364    6.44218

Average wins by position in NL West:  93.6 85.6 79.0 72.6 65.0
NL West           W    L    Pct3  Avg W  Avg L  Champions  Wild Card   Playoffs
Diamondbacks      23   15   .531   89.7   72.3   54.19041    6.69365   60.88406
Dodgers           19   18   .537   86.0   76.0   32.96834    7.79156   40.75990
Giants            16   23   .438   69.2   92.8    1.27575     .30636    1.58210
Rockies           15   23   .506   78.2   83.8    8.81159    2.91858   11.73016
Padres            14   25   .481   72.8   89.2    2.75392     .85496    3.60888

Average wins by NL Wild Card:  92.2

As the title says, the post-season odds report was compiled by running a Monte Carlo simulation of the rest of the season one million times. Current wins, losses and expected winning percentages are taken from the Adjusted Standings Report.

Expected winning percentages (EWP) for each team starts with their W3 and L3 from the Adjusted Standings. A regression is applied to derive the EWP for the rest of the season, which is going to be between the current winning percentage and .500. To allow for uncertainty in the EWP, a normal distribution centered on the EWP is randomly sampled, and that value is used for the remainder of the season in that iteration. To simulate the normal 4% home-field advantage, the home team gets a .020 point bonus, while the visitors take a 0.020 penalty. The likelihood of winning each game is determined by the log5 method.

At least, that's how it works in the regular version. For this, PECOTA adjusted version, the regression isn't done to the mean (.500), but rather to the PECOTA projection made at the beginning of the year (numbers which can be found here). The Yankees were projected to be a .580 team - and so the EWP described above will nudge their record towards .580, not .500. W and L are the team's wins and losses through yesterday's games.

Pct3 is the expected winning percentage, taken from W3 and L3, with the regression-to-mean component.

Avg W and Avg L are the average number of wins and losses each team finishes over the million season iterations.

Champions is how often, in percentage terms, this team won the championship of their division. Ties are not broken, but credited as 0.5 championships apiece (for a two-way tie), .333 apiece for a three-way tie, .25 for four-way, etc. This is why the final decimal place is not an error!

Wild Card is how often, in percentage terms, this team won the wild card. As with championships, ties are not broken, but apportioned among the tied teams.

Playoffs is how often, in percentage terms, the team either wins the division or the wild card.

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