Pythagorean Expectation: League of Ireland

Pythagorean Expectation for LoI

Pythagorean expectation is a concept originally from baseball.  Bill James derived an equation that approximates the win percent based on runs allowed and runs made.
win % = runs made 2 / (runs made 2 + runs allowed 2).

 It is a little more complex to apply to football, but some smart people have come up with different varieties of the equation that work very well for football to approximate points based on goals for and goals against. The one that I favour (for its relative simplicity) is copied below from here.
Pts = Games Played * 2.74 (goals for 1.32 / [goals for 1.32 + goals against 1.32])
It can be applied to predict a teams points total for the end of a season. It can also be used to check how efficiently a team is converting their goals into points.

The table so far for the League of Ireland is shown at the top. Most of the Pythagorean expectations are fairly accurate - although it does appear to over estimate the points in general. 

Galway, however, have accrued more points than expected. Have they been particularly lucky? Or efficient? They certainly scored goals when they needed them most with Galway scraping their two wins by a single goal and have avoided draws so far.

Shamrock Rovers despite scoring a shed load of goals and only conceding 3 goals have underachieved so far. They are about 3 points short of where they 'should' be based on the formula. They have drawn 4 games out of 9 and failed to score at all in 3 games.

 More pretty numbers that we have been following describing the League of Ireland 2014/2015 so far below.


TeamPWDLFAGDPtsProbShot %Save %SoTRTSRPDOPyth
Dundalk9720183152340%27%86%76%66%113022.54
Cork City9630162142123%36%89%71%61%124423.17
Shamrock Rovers9540133101929%27%89%64%64%116021.55
Bohemians9522945172%26%89%49%48%114918.36
St Patrick's Athletic943212931518%21%79%57%57%100114.64
Derry City9333880120%24%80%46%45%103512.33
Longford Town FC9234913-490%18%72%52%50%9019.39
Drogheda United9225813-580%26%78%35%40%10348.51
Sligo Rovers9144814-670%12%71%58%60%8307.97
Bray Wanderers9216712-570%32%77%29%34%10928.12
Galway United FC9207617-1160%20%71%34%38%9124.98
Limerick9036723-1630%16%70%36%41%8604.25

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