A few weeks ago, I took an initial (and someone rudimentary) dive into tying Statcast data to Ottoneu. Specifically, looking at the Fangraphs Points (FGpts) format. Like in real baseball, when the ball leaves the bat with a higher exit velocity, it is more likely to produce more favorable results. This was to be expected. The way the scoring settings for FGpts was developed was through linear weights, so it would make sense that the distribution of points per batted ball ties closely to reality. Today, I am going to look at the batted balls hit though the all star break (actually, just before the break as I pulled this July 6th) and examine the expected points per ball in play on specific batted ball types. Let’s get started.
So, for 2017 we can see that the average FGpts produced on a batted ball event is 1.525. Consequently, the average wOBA per batted ball event is .377 (NOTE: This is only wOBA on balls in play, and as such is higher than the league average wOBA on all plays of .321). Tying this back to basics is helpful. For example, we can see that two-thirds of the time a ball is put in play it results in an out. That singles account for nearly 64% of all hits, but 44% of all points on positive value balls in play (singles, doubles, triples, home runs). Home runs, by comparison, account for 14% of all hits, but 30% of all points on positive value balls in play.
One of the best resources in understanding statcast data is Andrew Perpetua’s xstats.org. In Andrew’s work, he classifies batted balls into 6 buckets based on their associated launch angles. For reference, here are the splits Andrew uses.
For the LA column, this can be read as a batted ball with a launch angle below zero degrees is a dribble ball with an average wOBA of .176. 10 corresponds to batted balls with launch angle between zero and ten, etc.
Using these same launch angle classifications, I wanted to see if the Ottoneu Scoring differed from the standard wOBA hierarchy of batted balls. As wOBA is often used as a proxy to determine FGpts value of a player, it would be helpful to know if one type of batted ball is being more heavily weighted by FGpts than by wOBA.
In examining the six batted ball types, FGpts values lined up with the wOBA hierarchy of most valuable batted ball types. Specifically examining DB.
We can see that so far in 2017, for balls recorded by statcast with a launch angle below zero, the average wOBA is .167. The average points per ball in play is .046. As we would expect, the majority of these batted balls are singles, and you can’t hit a home run on the ground. This is pretty standard. Looking at Ground Balls next, we would expect the value they produce to be greater than .046 points per batted ball, as we know that wOBA will be higher on these plays.
Well that’s a nice production bump. The FGpts value gained from hitting a ball between zero and ten degrees, as opposed to under 10 degrees is 1.979 points! You might be thinking to yourself, “1.979 points per ball in play does not seem like a lot” However, remember that the average points per ball in play for all batted ball types is only 1.525. We get a production bump in FGpts when moving from DB to GB, we should expect a similar bump from GB to LD.
Huzzah! We see a similar bump in production to what was expected. Let’s run through the other 3 batted ball types real quick.
Okay, a lot to digest, I know. What we wanted to see was that Fangraphs points was doing a good job of ranking the following categories. Pop-ups, are the worst batted ball type followed closely by dribble balls. After those two, ground balls are worse than fly balls, and low drives are worse than high drives. That is exactly what we see here. It appears, several years after it’s inception, that FGpts is still holding up as a scoring setting which is mimicking reality. To look at this a slightly different way:
|LA||Class||wOBA – 17||FGpts||delta wOBA||delta FGpts||FGpts/wOBA|
The wOBA increase on batted balls when going from a DB to a GB is .312, which corresponds to the 1.979 increase in FGpts per event we mentioned above. So, for each point of wOBA a hitter gains between these categories, there is an associated gain of roughly .063 points per point of wOBA. If we didn’t want to consider transitioning between batted ball types, we could take a more general view, and notice that on average 1.525 points per batted ball are scored with a wOBA of .377. On average, that would mean that for each point increase of wOBA on balls in play, we would gain roughly .04 FGpts. Hopefully, this is helpful in understanding the different batted ball types based on launch angle and how they correspond to Ottoneu. I know there’s a lot of information here.
Joe works at a consulting firm in Pittsburgh. When he isn't working or studying for actuarial exams, he focuses on baseball. He also writes @thepointofpgh. Follow him on twitter @Ottoneutrades