To rank pitchers I use the RPI ranking. The RPI is calculated by dividing
the # of runs given up by the # of innings pitched.
The Average Innings Pitched (AIP) is calculated by dividing total
innings pitched by the # of games thrown.
Multiplying the RPI x AIP gives you the average runs given up per game (RPG).
However a problem occurs when using the RPG to compare pitchers. Since relievers,
closers, and starters have different AIP the pitcher with less innings has an advantage over those pitchers who average more
innings.
Baseball statisticians tried to fix the problem by using 9 as the multiplier to calculate the ERA.
The problem exists still because all the pitchers now have inflated RPI's. But baseball used what they believe is fair
for everyone.
There isn't a perfect way to numerically compare pitchers. I believe the
fairest way is to use the RPI to compare pitchers. If you'd rather multiply the AIP and the RPI and get what a pitcher
averaged per game that's fine.
If you have a list of players not currently ranked and
would like me to include them please e-mail your requests.
