What makes your favorite baseball team win or lose? Inquiring minds want to know! The wonderful website Fangraphs.com can help you decipher the keys to success for any major league baseball team. Fangraphs.com gives you traditional statistics such as Batting Average and E.R.A., but these really do not tell you the keys to team success. We know that most of a team’s success is due to their hitting, fielding and pitching abilities. Fangraphs.com makes it easy to determine how any team’s performance in these areas affects a teams win-loss record.

Let’s look at the 2009 Yankees. Select them from teams and select Batters. Next choose Win Probability. The key number is the WPA ( Win Probability added) column. Johnny Damon, for example, has 3.72, indicating that in his plate appearances he added 3.72 wins more than an average player. The total of the WPA column for all Yankee batter’s was 10.33 wins, indicating that Yankee hitters contributed 10.33 more wins than an average hitting team.

Next select Pitchers and chose win probability. We can now see how Yankee pitchers contributed to Yankee wins. In his time on the mound Rivera contributed 2.82 more wins than an average pitcher while Chien-Ming Wang contributed 1.97 fewer wins than an average pitcher. Overall Yankee pitchers contributed 4.73 more wins than a team made up of average pitchers.

Finally, let’s look at Yankee fielding. Choose Fielders and look at the UZR (Ultimate Zone Rating Column). This tells us how many runs better than average a fielder is. For example, Johnny Damon’s fielding cost the Yankees 7.7 runs while Brett Gardner’s fielding saved the Yankees 8.5 runs. Basically 10 runs = 1 win. The Yankees fielders UZR total to -14.8. This indicates that Yankee fielding cost them 1.48 wins. Now adding up the contributions from the Yankee’s batting, pitching, and fielding indicates that the Yankees (as of August 8) were

10.33 + 4.73-1.48 = 13.58 wins better than average. The Yankee’s record on August 8 was 68-42, which is 13 games above .500!

We can gain unlimited insights from Fangraphs.com. For example, looking at the Devil Ray’s 2007 and 2008 fielding we can see that the Ray’s amazing 2008 season was primarily due to their amazing improvement in fielding. We can also find that Mike Lowell’s hip injury has cost the Red Sox 2 games this year due to his diminishing fielding ability.

Of course, general managers can use this information (and do) to evaluate trades and make salary decisions. For more explanation of how Win Probabilities and fielding ratings are computed see my book *Mathletics *which will be out in September 2009.