Graph of the Intermittent Time Period

Throughout the season, you’ll hear about run differential as a measure of a team’s success. While not perfect, run differential has been shown to be a good way to determine the skill of a team. It is, after all, the basis for Pythagorean Expectation and its variants. If you know how many runs a team scores and how many they allow, you have a good basis for predicting their future success.

The Phillies have been doing quite well in that department, as you may expect. Prior to Sunday’s games, the Phillies had the third-largest run differential in baseball and by far the best in the National League, besting the St. Louis Cardinals +129 to +48.

Here’s an overall look at MLB run differentials, followed by just the National League. (Click to enlarge)

The Phillies’ 498 runs scored and 369 runs allowed translates to a 72-41 record. As they were 74-39 prior to yesterday’s game, the two-game difference isn’t much and shows the Phillies are about as good as they’ve looked. With this run differential, the Phillies are a 103-win team over a 162-game season. Even with the loss yesterday, the Phillies are on pace for 105 wins.

This study, by David D. Tung, found that “The root mean square difference between the observed and¬†predicted games won is [4.0] games.” What that means is that the Pythagorean expectation will give you an idea how good a team is plus or minus four games. In other words, the PE says the Phillies are a 103-win team, but could actually be between 99-107 in terms of true talent. Basically, the Phillies are really freaking good.

The Playoff Odds Report at Baseball Prospectus, which uses similar but more intricate methods, puts the Phillies at 100% to make the playoffs, the only team in baseball to have risen to the peak. The next-best team in the NL is the San Francisco Giants at 87.9%. Furthermore, the Phillies’ simulated won-lost record comes out to 101-61, right in line with both our to-date results and the Pythagorean expectation.

It seems a bit hyperbolic, but whether or not they win the World Series, there is a very strong case to be made that the 2011 Phillies are the greatest team in franchise history. Through just 114 games, the Phillies already have the tenth-best run differential (remember, a counting stat) in franchise history and the fifth-best in franchise history in the live ball era. Prorating their run differential over 162 games gives them a +185 differential, which would be the third-best in franchise history behind the 1976 team (+213) and the 1887 team (+199).

Year G W L Ties W-L% Finish R RA Rdiff
1976 162 101 61 0 .623 1st of 6 770 557 213
1887 128 75 48 5 .610 2nd of 8 901 702 199
1894 132 71 57 4 .555 4th of 12 1179 995 184
1977 162 101 61 0 .623 1st of 6 847 668 179
1899 154 94 58 2 .618 3rd of 12 916 743 173
1893 133 72 57 4 .558 4th of 12 1011 841 170
1892 155 87 66 2 .569 4th of 12 860 690 170
1993 162 97 65 0 .599 1st of 7 877 740 137
2010 162 97 65 0 .599 1st of 5 772 640 132
2011 113 74 39 0 .655 1st of 5 498 369 129

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