Simply, you first determine a ball players's on base percentage, his slugging percentage, and the combination of the previous two equations through addition called On Base Plus Slugging. Then you calculate the league's on base percentage, slugging average, and ops. Then divide the the player's stat into the league stat [with the ob%, slg%, and ops]. Finally, you leaf through a book or surf the internet, or get a fancy computer program to determine the player's home ballpark value, and finally divide the already relative value by the ballpark factor. In order to display longivity, players must have at least 5,000+ plate appearances to qualify for this stat.
example : Dick Allen
381 OB% + 534 SLG%= .915 OPS
The league average during his career was 356 OB% + 346 SLG%=.702
OB EAV=107.222 [106.880 w/ballpark adjustment]
SLG EAV=154.335 [154.130 w/ballpark adjustment]
OPS EAV=130.342 [130.169 w/ballpark adjustment]
An above average EAV is over 100.000, while below average is .999 and below. These numbers represent the percentage above or below the league average.
While it is definately an asset for a ball player to display his individual skills, that is simply not a complete way to examine the player. He is merely competing against hiself. When you compare statistics in this form, it can be very misleading for various reasons. Other ballplayers may be having better careers on paper, but that is independent of the non-relative stats, therefore missing the complete picture. In short, this is called talent.
A three dimensional view of measuring stats is by dividing them by the league average. You compete against other player's statistics, which in turn shows the players net measurement instead of raw talent. This is a much more important measuring stick because it is actual competition against each other versus competition against the individual, who in turn has his stats posted of individuals competing with themselves than against each other. In short, value is much more important than talent because it is value that precisely documents who are the better players, while talent shows how good an individual player is while not taking into account the players he is competing against. In the long term, value equals wins.
MORE TO COME SOON!