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Similarity Scores Glossary
 
Introduction - Batting - Pitching - Fielding - Miscellaneous - Leaderboards - Similarity Scores - Ratings
 
Similarity scores were introduced by Bill James in his book The Politics of Glory (pp. 86-106). To compare one player to another, start with 1000 points and then subtract points based on the statistical differences of each player. Note that a player must have 100 innings pitched or 250 at bats before being considered and to be truly accurate you need to look at whole careers.

Batters

  • One point for each difference of 20 games played.
  • One point for each difference of 75 at bats.
  • One point for each difference of 10 runs scored.
  • One point for each difference of 15 hits.
  • One point for each difference of 5 doubles.
  • One point for each difference of 4 triples.
  • One point for each difference of 2 home runs.
  • One point for each difference of 10 RBI.
  • One point for each difference of 25 walks.
  • One point for each difference of 150 strikeouts.
  • One point for each difference of 20 stolen bases.
  • One point for each difference of .001 in batting average.
  • One point for each difference of .002 in slugging percentage.

To this there is a positional adjustment. Each position has a value, and you subtract the difference between the two players position.

  • 240 - Catcher
  • 168 - Shortstop
  • 132 - Second Base
  • 84 - Third Base
  • 48 - Outfield
  • 12 - First Base
  • 0 - DH

Pitchers

  • One point for each difference of 1 win.
  • One point for each difference of 2 losses.
  • One point for each difference of .002 in winning percentage (max 100 points).
  • One point for each difference of .02 in ERA (max 100 points).
  • One point for each difference of 10 games pitched.
  • One point for each difference of 20 starts.
  • One point for each difference of 20 complete games.
  • One point for each difference of 50 innings pitched.
  • One point for each difference of 50 hits allowed.
  • One point for each difference of 30 strikeouts.
  • One point for each difference of 10 walks.
  • One point for each difference of 5 shutouts.
  • One point for each difference of 3 saves.

If they throw with a different hand and are starters subtract 10, relievers 25. For relievers you half the winning percentage penalty and the winning percentage penalty can up to 1.5 times the wins and losses penalty. Relievers are defined as more relief appearances than starts and less than 4.00 innings per appearance.

 
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