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.


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Schu
Member
Schu

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

scatterbrian
Guest
scatterbrian

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

MGL
Guest
MGL

Brian,

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?

Colin Wyers
Guest

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.

81
Member

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?

Temo
Member
Temo

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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