PBR - Fans often contend a team's success hinges on how it performs during the first month of the season.
Though logical, this assertion often is inaccurate.
A recent study conducted by the Review of Phillies' monthly winning percentages (dating from 2000 to 2011) indicates a minor correlation between April success (or lack thereof) and end-of-season winning percentage.
Instead, the study indicates performances in the months May and June are more telling than April.
To begin the study, I found Phillies' month-by-month records from 2000 to present on Baseball Reference and placed them in Excel. I then ran a multiple regression analysis with the Y variable equaling season winning percentage and the X variables equaling the various monthly winning percentages. I did not include the instances where games were played in March or October.
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| PHI monthly winning percentages, 2000 - 2011 |
Using the information above, the regression analysis resulted in the following coefficients (all statistically significant):
- April: .127
- May: .244
- June: .219
- July: .143
- August: .175
- September: .178
To further examine the importance (or lack thereof) April has in forecasting success, I looked at every club dating to 2000 that won the World Series. I made note of their April winning percentage and subtracted April's won-loss record to find overall season winning percentage. I did the same with the Phillies and charted the following (* means March games added in April, October games added in September):
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| Phillies WPct in April and End of Season |
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| World Series Winners in April and End of Season. |
The correlation for the Phillies was .652, meaning the winning percentages (April and non-April) were moderately linked, but not significantly. In contrast, the correlation of April winning percentages and overall winning percentages of World Series winners from 2000 to present was -.470, meaning April performances are lousy indicators of future success.
So, what does all of this mean?
Put simply, you can't read too much into April performances. Sure, winning early is a great opportunity to build a lead in a division, but the season is a marathon, not a sprint.
Sustained success in the middle months of the season is much more meaningful than a solid winning percentage in April.
