I thought they said that they did not take postseason into account.
As I understand it the ratings are initially determined by the real life stats from the last 3 years
2014 - 50% of the total
2013 - 25% of the total
2012 - 25% of the total
Then from there they make tweaks for a few players We also don't know how much specific certain stats are weighted in the final calculation.
But except for those players that may have had their rating tweaked he was ranked using the same system as every other pitcher.