Early Returns Troubling on the Ground

While updating my numbers on the average run and out values of various batted ball types this past afternoon, I noticed what looked like an anomaly when it came to ground balls in the American League this season. The average run value of a ground ball was roughly half so far in 2010 of what it was in 2007-9. I assumed there had to be something off with my code and my first check was to look at the National League, but that did not turn up any unexpected results.

Curious, I spit out the odds of an out occurring on a groundball in each year as a chart. In years past, right around 66% of all ground balls were turned into a single out. An additional 7% caused a double play. The National League is almost exactly the same though it has had more single outs and slightly fewer double plays on account of there being fewer runners on base on average.

However, so far in 2010, those ratios are up to 68% and 7.5% in the American League while the National League shows no significant deviation. Now, that does not seem like much of a change from average in the AL numbers but consider that a ground ball is the single most likely outcome for any plate appearance. There are lots of them and any movement can reap big changes.

In 2009, hitters batted .239 on ground balls. That’s down to .210 in 2010 and there’s been a rise in double plays turned (and a triple play as well). All that adds up to a lot more outs, about 163 in fact. Over just under 4500 ground balls, you have outs up about 4%, but only in the AL. What’s changed? I have no idea, but right now ground ball hitters are having quite a tough time of it.

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Matthew Carruth is a software engineer who has been fascinated with baseball statistics since age five. When not dissecting baseball, he is watching hockey or playing soccer.

26 Responses to “Early Returns Troubling on the Ground”

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  1. Schu says:

    Probably has a lot to do with the recent focus on defense.

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    • scatterbrian says:

      I was thinking the same thing. Have there been fewer errors on groundballs in the AL?

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      • MGL says:


        I doubt that the teams that are emphasizing defense are paying much attention to players’ error rates. IOW, when someone says that teams or leagues are emphasizing defense more, they are not talking about error rates (fielding average) – they are talking about the ability to field balls and turn them into outs – range essentially.

        In any case, BA on ground balls is not affected by error rates, right?

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      • Colin Wyers says:

        MGL, doesn’t that depend on what’s causing the change in error rates? If it’s a distinction between error and out, then no. If it’s a scoring change from an error to an infield hit, then it has an effect on BABIP, yes.

        Now, I don’t think that explains what Matthew is showing here, but it is something to consider.

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    • 81 says:

      In previous years the promotion of worm burning prospects has been muddled by most team’s inability to accurately profile these pitchers in the majors. A player like Randy Wells (career 48% ground-ball percentage) can go relatively under the radar while surrounded by typically inferior minor league infield defenses. This undoubtedly results in an inflated ERA which might not pass the stink-test of a non-sabermetrically oriented scout (of which I’m sure the Cubs organization has many). As more teams adopt a more sound approach towards assessing these types of players you will naturally see an influx of talented ground-ball specialists.

      On a mostly unrelated note; should extreme ground ball pitchers expect to sustain higher LOB% due to the value of a double play?

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      • Temo says:

        It’s usually balanced out by extreme ground ball pitchers having below average K rates (which is even more effective at stranding batters).

        Roy Halladay doesn’t apply here.

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  2. tomsteele says:

    I blame Brendan Ryan.

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  3. Nate says:

    I blame Mike Napoli.

    Career Averages:

    FB% – 46%
    IFFB% – 12.1%


    FB% – 19%
    IFFB% – 0%

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  4. PhD Brian says:

    This is normal variation. In every normal curve you occasionally get results that do not appear normal, but are. You are just farther to the right on the curve. It is normal.

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    • dp says:

      I thought the same thing–this is likely statistical fluctuation. However, if I did the math correct, it is highly unlikely—.00008 probability–so probably not. I’m stumped for reasonable explanations, however. A couple questions that could help clarify are: does this continue a trend from the end of last year? Which teams have the biggest changes in ground ball out numbers over the past year? Are the changes across all teams or concentrated on a subset of teams? As asked by someone else, is there usually a seasonal variation?

      Have their been any changes in the sources for balls or bats in the AL this year?

      This is interesting and fun, I hope someone gets to the bottom of it.

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    • Colin Wyers says:

      Quickly eyeballing it, it seems like it’s around a 4 SD change. I dunno. Is it POSSIBLE that there’s a 4 SD change, simply due to random chance. Yes, certainly. But I think it bears SOME examining.

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  5. At least 150 of those outs are Teixeira’s fault. #thisisforthosethatdonotsensesarcasm

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  6. Louis says:

    Just pondering, but between the new stadium in Minnesota, and the new turf in Toronto, could the ground balls being batted in those two stadiums be running a little more true than in past seasons, and not giving players as many favourable bounces. Could explain part of the variance at least.

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  7. Temo says:

    Can we get April 2009 numbers on this? It could be a seasonal thing, where grounds are better kept in the spring, thus resulting in easier to field ground balls.

    I concede this would not explain why the NL does not show much difference (though BABIP on GBs in the NL is down a bit from last year)

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  8. Temo says:

    The main culprits, in terms of BABIP on GB against, are the Red Sox (.203 BABIP), Blue Jays (.180 BABIP), A’s (.192 BABIP), Rays (.166 BABIP), and Mariners (.146 BABIP).

    These teams last year did far worse than they’re doing this year: Red Sox (.244), Blue Jays (.213), Rays (.224), Mariners (.226), A’s (.255)

    On the high side, I did not find any team with a significantly more than average BABIP on GBs against.

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  9. sabernar says:

    I don’t know if there are less runners on base, but there are definitely FEWER runners on base.

    Come on, at least use proper grammar in your articles. ‘Less’ is for things you can’t count and ‘fewer’ is for things you can count.

    Because chicken pox is going around, there are fewer kids in class.
    Since I’ve been on medication, I feel less dizzy.

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    • better? says:

      I don’t know if I want less grammar police here, but definitely more few.

      Glad to hear you’re on medication.

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    • Dave says:

      You’re right, but you do the cause of grammer no favors with your attitude, Buster. Free article, minimal editing, so point it out politely (if you feel the need) and move on. And I’m glad the medication is working out for you.

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  10. jwm says:

    JJ Hardy switched leagues. That’s the cause.

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  11. pft says:

    HR are down as well in the AL. By a fairly significant 18% I might add vs same time last year (and this spring has been milder than last year in most places). Might be the ball. Although the NL and AL both use the same balls, supposedly, teams wanting to emphasize run prevention might be able to humidify it and reduce the balls COR, which affects GB and HR equally (a lower SOB means GB take longer to get through the IF). Maybe thats why HR hitters were not much in demand this off season, there was a plan to suppress HR in the AL (15% higher HR rate than the NL last year). No proof of course, just a hypothesis that can not be proven, only disproven.

    The NL did not get a boost in HR last year like the AL, so there being no change in GB BABIP is consistent with my hypothesis.

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  12. Sky Kalkman says:

    Would controlling for batter matter? Maybe high-contact speedy players who hit ground balls and are successful with them are being weeded out of the league? Their replacements are more successful with fly balls, and struggle when they hit ground balls?

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  13. Mike Kalina says:

    I heard an announcing crew talking about how Baltimore is cutting the infield grass a lot higher this year which is slowing the ground balls down a lot. Perhaps this is a trend this year in AL parks.

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