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Sabermetrics: Game Score

If you're a regular reader of our site you may have noticed me starting to use the statistic Game Score to evaluate pitching performances, more and more

Game Score is a Bill James created statistic that takes a pitchers final pitching line and turn it into a single number. Introduced in 1988, Game Score uses a 0-114 scale to rate a pitcher. To get a score of 114 a pitcher would have to nine innings and strikeout every batter he faces. Most pitching performance fall in the 0-100 range, although there are cases of a pitcher having a Game Score above 100. To get a pitchers Game Score do the following:


Screenshot taken from Baseball Reference

Eight easy steps and you're done. If you can fill out a scorecard you can figure out a pitchers Game Score. At the very least, It would give you something to do during the later innings.

The current most popular way to evaluate a pitchers single game performance is the quality start, which has only two qualifications: go at least six innings and allow three runs or less, that's it. That's even simpler than Bill James Game Score, and probably one of the reasons why it's caught on and Game Score has stayed relatively unused, even within the sabermetrics community. Quality start is a very vague statistic though and doesn't tell the entire story of an outing, Game Score does.

A study by Jeff Angus showed that a Game Score of 50 typically means that the pitcher gave their team slightly over a 50% chance to win the game. The numbers don't match up exactly, but they're close enough that you get a good idea of how much a pitching performance contributed to that teams chances of winning based of Game Score.

Last summer, John Dewan suggested anything above a 65 should be considered a gem. I won't go into detail regarding that idea, but I did want to give some idea how to gauge a performance. I've read in another location, and I apologize for not being able to find the source and give proper credit, that anything above 60 is considered a great start. According to Angus' study a 60 Game Score resulted in a 62% winning percentage for teams in 2007.

What I like about Game Score is that it gives you a single number in which to compare starts between the pitcher himself and his rotation mates. I also like that it's an all inclusive stat.

Earned Run Average is just that it averages runs per nine innings, it does not account for hits, walks, unearned runs and strikeouts. You know that already, though, and that's why you use Fielding Independent Pitching and it's variants which only looks at what a pitcher can control, hits walks and strikeouts. It doesn't, however, take into account any runs scored. Game Score accounts for both.

Game Score isn't perfect and has its own flaws, and I'm not suggesting it replace any of the other statistics, but it is a better indicator of a pitching performance than the more popularly used Quality Start statistic.

After the jump we'll look at some observations of Game Score for the Astros 2012 season and some past observations.

  • The Astros as a staff have had eight Game Scores above 60 this season, four of which Dewan would describe as gems.
  • The Astros have had eight games in the 50-60 range. So in 16 of the 29 games the pitching staff has given the team a greater than 50% chance of winning the game.
  • The pitcher with the best Game Score this season was Wandy Rodriguez's fourth start April 22, against the Los Angeles Dodgers. Wandy's line: 7IP, 3H, 0R, 3BB, 6SO for a Game Score of 74.
  • The pitcher with the lowest Game Score this season was Kyle Weiland's second start April 16, against the Washington Nationals. Weiland's line: 5.2IP, 10H, 6ER, 4BB, 2SO for a Game Score of 23.
  • Wandy Rodriguez is the only starter, with more than two starts, to have an average Game Score above 50, with 59.14.For comparison Justin Verlander's average Game Score this season is 66.5.
  • In Jordan Lyles one start he posted a 54 Game Score.
  • Bud Norris is very close to 50 with a 49.67 average, which I guess of could of rounded up to 50.
  • The six pitcher no-hitter by the Astros in 2003 against the New York Yankees resulted in a 97 Game Score.
  • In 1977 J.R. Richard's average Game Score was 60.39. 20 years later Daryl Kile would post a 61.12 Game Score in 1997.
  • Pedro Martinez's 2000 season, quite possibly the best pitched season ever, resulted in a 73.28 Game Score average.

There are other stats that can highlight some of the observations I've made above, but somehow they aren't as much fun to look at.


Baseball Reference Play Index Glossary

"Gem: A Pitching Masterpiece" by John Dewan

"Does "Game Score" Still Work In Today's High-Offense Game?" by Jeff Angus

Game Score - Wikipedia