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

Leave a Reply



  1. Dave

    August 08, 2011 07:40 AM

    It would be interesting to look at run ratio, i.e., runs scored / runs against.
    A good pitching / average hitting team will be in more low scoring games where runs come at a premium and differences aren’t as pronounced. I’d say a 4-2 win with one of our aces is just as dominating as a 6-3 win by another team with just decent pitching. Meaning that the losing team never had as good a chance of winning that 4-2 game against our ace as the team who lost by 3 runs against middle of the road pitching.

    It would at least be interesting to see how the run ratio correlates with actual W-L records compared to run differential.

  2. Nick

    August 08, 2011 09:21 AM

    I still think that its amusing that the Giants have a negative run differential now (it was slightly positive pre-Phillies series). Both the Phils and Giants are good pitching teams but its rather indicative that their offense can’t even manage a positive run differential to go with those 60+ wins.

    I’m also surprised the numbers show the Giants getting to the playoffs 87% of the time. The Diamondbacks seem to be sticking around and wouldn’t the Braves be the Wild Card team at this point? Unless the Diamondbacks/Giants creampuff schedule lets them walk into the playoffs.

  3. Crud Muffin

    August 08, 2011 09:32 AM

    Somewhat off topic, but does anyone find it amazing that the 2001 Mariners had a +300 run differential?

  4. Robby Bonfire

    August 08, 2011 12:42 PM

    What jumps out, to me, regarding the difference between teams, is Cincinnati having a 12-run edge over Milwaukee, a much stronger team than Cincinnati which may pose the strongest N.L. challenge to the Phillies, after game 162.

  5. Cutter McCool

    August 08, 2011 01:36 PM

    @Robby Bonfire. The team that poses the greatest threat to the Phillies, “after game 162,” is the Giants. Why? Because they can’t score runs off Lincecum or Cain, and they will face them 4 times in a 7-game series. The Giants pitching is the #1 reason that Amarro brought back Cliff Lee.

    Their front office will never admit it, but they’re praying that the Diamondbacks take the NL West and the Giants miss the playoffs.

    Throughout their current run since 2008, the Phillies have never won a playoff series when they’ve been pitted against an equal or better rotation than theirs.

    And since a likely NLCS is Braves & Phillies, the front office would prefer not to face their staff either.

  6. Steven S. Stevens

    August 08, 2011 01:38 PM

    I was wondering the exact same thing as Nick re: Giants’ playoff chances. The Giants have all of a half-game lead on the D-backs and a negative run differential, compared to a +22 in Arizona. To see the Giants that far ahead given

    Coolstandings, meanwhile, has the division odds at 51% Giants, 46% D-Backs, and about 3% others. ( )

    Pretty crazy how different the two can be. Apologies for derailing the discussion from how awesome the Phillies are (because, let’s be honest…duh.) but do you have an idea of what goes into BP’s projections?

  7. Steven S. Stevens

    August 08, 2011 01:40 PM

    * To see the Giants that far ahead given the stark run differential disparity is a bit interesting.

    comment got cut off there, my bad

  8. Richard

    August 08, 2011 03:21 PM

    “do you have an idea of what goes into BP’s projections?”

    it’s based on part on their updated PECOTA projections for the players on each team… so they probably expect SF to play better than they have, and Arizona to tail off..

  9. Robby Bonfire

    August 08, 2011 08:03 PM

    Cutter, You could be right, but let’s see how it plays out. The Giants, even with Beltran, are hurting for offense, and WS champions just don’t repeat, anymore, given the three-tier hill to climb in the post season, every year. The Cardinals have been blowing hot and cold all season, even with one of the two best managers in the game. Let’s just say I respect and fear Milwaukee the most of all the pretenders to what should be a Phllies N.L. crown. That, plus no one is refuting my statement that Milwaukee is better than Cincinnati.

  10. Nick

    August 08, 2011 08:16 PM

    Let’s all remember that despite this chart (which I don’t believe – look up the schedules, unless Arizona blows it, they very well could win the division), the Giants are contending in the hottest division race in the league. And yeah, hotter than the Yanks and Sox because the Yanks just can’t beat the Sox at all, and the loser of that goes via the wild card. Meanwhile, the Braves will, more than not, get the wild card while the loser of Arizona and San Fran goes home.

    I’m gonna be saying some prayer for Arizona – they just don’t scare me as much as San Fran.

  11. Phillie697

    August 08, 2011 08:59 PM


    That analysis has already been done. How do you think they came up with the Pythagorean Expectation in the first place? The strong correlation isn’t with run scored/run allowed. Read the Wiki article Bill linked to.

    While it intuitively makes sense that a 9-1 win is the same as a 2-1 win even tho the run differential is great, over the course of 162 games, it evens out. No team is going to win every game 9-1, just like no team is going to win every game 2-1.

  12. Matt H

    August 09, 2011 03:05 AM

    Your interpretation of MSE is a little off. If you’re looking for a confidence interval, then for example in the paper you cited it’s closer to +/- 8 games.

    And I wouldn’t call the range an attempt to bracket “true talent” – this is a baseball blog so all I’ll say is that it’s a prediction of outcomes based on uncertainty both about the estimator of “true talent” and the randomness of run generation in any season.

    Cool post though. Dave hit the nail on the head, intentionally I think, when he compared the 6-3 game with the 4-2 outcome. Run differential should always be expressed in stat-friendly baseball blogs as a percent of runs allowed, if you believe that the run generation process follows an independent (and non-shifted) Weibull distribution. And who doesn’t believe that?

    Wait, now everyone thinks the distribution is shifted? Forget what I said earlier, the ratio is no longer sufficient and Dave is clearly a moron.

  13. Dave

    August 09, 2011 10:30 AM

    Ha! I doubt run scoring follows a Weibull distribution, probably closer to a Poisson.

    @phillies697: I wasn’t saying a 9-1 win was the same as a 2-1 win. But i was saying a 6-3 win was the same as a 4-2 win, in the sense that you scored twice as many runs as the opponent. Basically run differential favors a high scoring offense w. average pitching team (e.g. Red Sox) more than it does an average offense w. excellent pitching team (e.g. Phillies). The phillies actually have a better RS/RA ratio; Sox RS/RA = 1.305. Phillies RS/RA = 1.344. But they are 17 under in terms of absolute run differential.
    Can you link to the analysis that looked at correlation of the ratio of RS divided by RA in relation to actual W-L rcord? I’m sincerely interested.

  14. Dave

    August 09, 2011 10:36 AM

    I just read that Wiki article. I don’t think i ever actually looked at the pythagorean expectation formula. But yeah that definitely uses something closer to the ratio of RS and RA then it does the absolute difference. I guess because the +/- is always listed with the pythagorean projection i figured the expected W-L came directly from the +/-.

  15. Phillie697

    August 10, 2011 12:12 AM


    Glad to be of help 🙂 I mean, when you read the word “Pythagorean,” it should have suggested to you it was something a bit more complicated than simple run differential 🙂

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