Wednesday, June 05, 2024
Spray Angle is not needed, part 32
I have to write one of these blog posts every year because folks are so disbelieving. And it's not just my research. I MUCH prefer when others do this research so that there's no conflict of interest.
I'll lay out my method, and you can feel free to reproduce it however you can. There's some data you may not necessarily have, but you'd be able to estimate it.
Anyway, here we go. Again.
First the data: 2016 to present (thru Jun 4, 2024), regular season and playoffs. Only hit-into-play. We want actual wOBA and xwOBA. Minimum 500 batted balls for each batter over the entire time period. This gives me 593 batters. Hopefully you get something pretty close to that.
Next, we create a spray tendency for each batter. In the past, I would just take all their battedballs to create their spray tendency. But, inspired by the point Ben Clemens recently made (who was studying a similar issue), this time I've focused on batted balls with a launch angle of 4 to 36 degrees, for balls hit 200+ feet. This is basically line drives and flyballs, and the type of batted balls that folks talk about when they talk about pull hitters and spray hitters.
But, just for completeness, I'll also do it my usual way of looking at all batted balls to establish the spray tendency. I'll do that at the end. For now, we'll follow the Clemens-inspired approach.
For the 593 batters, I take the 10% most extreme pull hitters. There's 59 of them. Their spray tendency is a pull of 9.5 degrees. Then I take the 20% next most extreme pull hitters. That's 119 batters with a spray tendency of -7.0 degrees.
I take the 10% most extreme spray hitters. There's also 59 of them, with a spray tendency of +1.6 degrees. The next 20% are at -1.6 degrees. Finally, the middle 40%, 237 batters, have a spray tendency of -4.3 degrees.
Next, for each group, we look at their actual wOBA and their xwOBA. Now remember, the xwOBA does NOT look at a batter's spray direction, whether at a single play level, or at a player tendency level. It is simply ignored. So, if we find that there is a difference between actual wOBA and xwOBA then this is evidence that the spray variable needs to be added to the model. If they are a match, then we don't need it (or at least, we haven't found any evidence with this method that it is needed).
What do we find with the most extreme pull hitters, those at -9.5 degrees of spray? Actual wOBA of .386, xwOBA of .385. How about going the other way, the most extreme spray batters, those at +1.6 degrees of spray? They have a .362 actual wOBA... and .362 xwOBA. Identical.
How about the rest of the three bins? Bin 2 is .379 actual and .379 xwOBA. Identical. Middle bin is .370 actual and .370 xwOBA. Identical. Bin 4 is .363 actual and .365 xwOBA.
So... yeah... we don't need to consider the spray tendency of the batter to model their effectiveness.
***
I said I would rerun everything doing it my usual way of using all batted balls to establish spray tendency. The results are almost as boring, but I'll lay it out, from bin 1 (most pull tendency) to bin 5 (most spray tendency). Actual wOBA first, xwOBA second, difference third. Ready?
- -12 degrees, .382, .385, -.002 (rounding)
- -10 degrees, .372, .371, +.001
- -8 degrees, .378, .379, -.001
- -6 degrees, .364, .363, +.001
- -3 degrees, .348, .345, +.003
So... yeah... as it turns out, it doesn't really matter how I establish the spray tendency. We just get similar conclusions.
***
Now... How? HOW? HOW is it possible to ignore spray tendency and still be able to get the player wOBA to match to their xwOBA? Simply put: opposing teams know the pull/spray tendency of the batters and position their fielders accordingly. How about the HR? Well, that's true, but if you miss the HR, guess what, there's an outfielder who was positioned close by to turn that almost-HR into an out.
The reality that we found in 2016, when we had so very little data, such limited data, that allowed us to ignore the spray variable is being upheld with tons of more data. And this conclusion has been reinforced by other researchers who also found the same thing.
Long story short: while you need the spray angle to describe the PLAY, you do NOT need the spray angle to describe the (effectiveness of the) player. You can use the spray angle to show the PROFILE of the player, but it won't alter our opinion as to their overall performance.
I'll see you again in six months, where I'll do similar research in different ways. Again.
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