This one is obviously based on Bill James' Win Shares system. I adjust the Win Shares for season-length, as described in the normalization post.
I give an individual grade for each of the following: 3-year peak; 5-year consecutive peak; 7-year peak; WS per 162 games (or WS per 100 IP, for pitchers); and career WS. My goal is to blend peak measures with career totals. So in addition to giving grades in those areas, I also have a combo formula that gets a grade. The combo formula consists of taking the square root of the product of WS per 162 games (or WS per 100 IP) times career WS.
For each position played, and each of those WS categories, I examined the numbers achieved in those categories by actual Hall of Famers (categorized by position) and developed a scale to apply to the players under evaluation. After applying the grades in those categories, I end up with a Win Shares GPA, which determines the grade that goes into the player's overall GPA.
I made some special adjustments up through 1909. From 1871-1909 the ball was put in play a lot more than today, because pitchers essentially started the action. Win Shares assumes that defense is 48% of the game. Defense is split into pitching and fielding, but pitching gets twice as much weight as fieldign. That is not appropriate for the earliest years in baseball.
In my system, from 1871-1880, I recalibrate Win Shares to treat pitching and fielding as 50-50 on the defensive side. That means a reduction in Win Shares for pitchers, and increases in Win Shares for fielders (shared with teammates). From 1881-1886, I recalibrate Win Shares to treat pitching and fielding as 57-43 on the defensive side. From 1887-1893, I recalibrate Win Shares to treat pitching and fielding as 60-40 on the defensive side. From 1894-1909, I recalibrate Win Shares to treat pitching and fielding as 63-37 on the defensive side. Beginning in 1910, I leave the split "as is" at 67.5-32.5.
My Win Shares grade gets 1.5 times the normal weight in the GPA, because it is one of the preeminent uber-systems.
