We've altered Bill James' original Win Shares formula a bit. Specifically, we've credited players with negative Win Shares, which Bill James doesn't do, and we've toned down the credit that Win Shares gives players for saves, because we think it's more accurate in today's save-happy environment.
We've also included two new Win Share stats. One is Win Shares Above Average (WSAA). WSAA is a refined approach to Win Shares, in which each player's total Win Shares are compared to the Win Shares an average player would have received, given that player's time at bat, on the mound or in the field (listed as Expected Win Shares). This is an important adjustment to Win Shares, as we discovered during the offseason. 2003 WSAA were calculated (and explained further) in this article.
If you like to compare Win Shares to replacement levels (which I recommend), then you can calculate the replacement level as a percent of expected Win Shares. Anywhere from 75% (about 60 wins) to 50% (2003's Detroit Tigers) is appropriate. We've also listed Win Shares Percent (WSP), which is a Win Shares "rate stat" -- a measure of the player's contribution, given his playing time. The math is WS/(2*ExpWS).
If a player has played for multiple teams during this time, his win shares are broken out for each team. Note that the player position is the one he has played most frequently during the year. As a result, Fielding Win Shares may include shares that have been earned at other positions. If a player has no position listed, it means he has not yet played in the field this year.