- Start with 50 points.
- Add one point for each out recorded, so three points for every complete inning pitched.
- Add two points for each inning completed after the fourth.
- Add one point for each strikeout.
- Subtract two points for each hit allowed.
- Subtract four points for each earned run allowed.
- Subtract two points for each unearned run allowed.
- Subtract one point for each walk.
The maximum possible game score in a nine-inning game while allowing no baserunners is 114, possible only if a pitcher goes nine innings while striking out every batter he faces and facing three batters per inning. The pitcher receives 50 to begin with, and loses no points because there are no hits, walks, or runs of any kind. He receives 27 points for the 27 outs, and 10 points for five innings completed after the fourth inning, for a total of 87. In this "perfect score" scenario, the pitcher would have to strike out every hitter he faced, netting him an additional 27 points, for a grand total of 114.
The maximum possible score actually involves an extremely unlikely scenario in which three base runners reach base each inning on wild pitches or passed balls on third strikes. If this were to happen such that no one scored, and the pitcher recorded all outs by strikeout, a pitcher could theoretically record six strikeouts per inning, and thus 54 for the game, netting him 54 points in addition to the 87 he would have received as described above, for a total of 141.
Highest achieved scores
The highest game score for a nine-inning game in the history of baseball was Kerry Wood's one-hit, no walk, 20-strikeout shutout performance for the Chicago Cubs against the Houston Astros on May 6, 1998. His game score was 105 (50 + 27 + 10 + 20 – 2). Matt Harvey's game score of 97 in a nine inning, no run, one-hit, no walk, 12-strikeout performance against the Chicago White Sox on May 7, 2013 is the highest by any pitcher in MLB history in a non-complete game (the Mets won the game in 10 innings)..
Higher scores have been accomplished in extra-inning games. Harvey Haddix scored a 107 for the game in which he took a perfect game into the 13th inning. Juan Marichal and Warren Spahn scored 112 and 97, respectively, during a complete game 16-inning match up. In their famous 26-inning duel from 1920, Joe Oeschger scored 149 and Leon Cadore scored 141.
The lowest game score in baseball history was Allan Travers' 26-hit, 24-run start for the Detroit Tigers on May 18, 1912. His game score was a −52. This performance only came about because the regular Tiger players staged a strike in protest of Ty Cobb's suspension. To avoid a forfeit, local college players (including Travers) were enlisted as impromptu fill-ins. The lowest game score since 1957 was Oakland pitcher Mike Oquist's, who allowed 16 hits and 14 earned runs in five innings on August 3, 1998, for a −21.
The game score concept expands on Major League Baseball's official definition of a quality start. MLB defines a quality start as six or more innings pitched while allowing three or fewer earned runs. The game score system defines a quality start as a game score above 50.
The advantage that the system has over the official definition is that it allows a statistician a better view of the degree of quality in a pitcher's performance. Game scores can be quantified, and a pitcher's performance tracked over time. It is also possible to compare different pitchers. If one averages a 60 and another averages 55, presumably the first pitcher has had a better season.
In terms of high scores, the system favors current pitchers. It is difficult to achieve a very high score in a game without amassing a substantial number of strikeouts. In earlier eras, even for the very best pitchers, strikeouts were less plentiful. For instance, Cy Young's two no-hitters earned scores of just 90 and 88 due to their low strikeout totals (three and two, respectively).
Career totals for some pitchers
The total number of game scores listed for each pitcher are starts in which he reached 90 points or higher. The parenthetical totals represent the highest score in the pitcher's career, and the number of game scores equal to or greater than 100 (if any). This is not a complete list and includes only pitchers with five or more games of 90 or higher (through 4/11/2013).