When talking about launch angle much focus is on swing plane and of course rightfully so. Many players like Jose Bautista, Josh Donaldson, Daniel Murphy and Justin Turner have demonstrated that it is possible to change the swing and achieve spectacular gains in power output.
However also the plate discipline by the hitter and the way he is pitched have an effect. Looking at Statcast data the average launch angle in the upper third oft he zone is around 20 degrees, while it is only 5 degrees in the lower third. Of course that doesn’t mean higher pitches are better to swing at, high pitches are also known to induce more pop-ups and whiffs on certain types of fastballs (high spin) but for players who have trouble to elevate the ball it can make sense to swing a little less in the lower part of the zone. On the other hand a high whiff or popup rate type of player who has a good launch angle it might make sense to leave the high pitches alone.
I did a breakdown of the zones for right-handed hitters. I looked for LA but also exit velocity to see where the good parts are. Unsurprisingly pitches over the plate do better in both LA and EV. Inside pitches did better in the LA but worse in the EV and for outside pitches it was vice versa, better LA but worse LA.
Just high and low both did about the same in EV but high did better in LA by far. When looking finer we could confirm that the combination of low and away gave the lowest launch angles and up and in gave the highest, but up and in also by far yielded the worst exit velocities probably because there is the least space to get the barrel around up and tight – so there is a trade-off between EV and LA.
Over the plate is, of course, good and middle pitches too as are up and away and down and in. The down-away to up-and-in axis is probably to avoid.So ideally a batter would have a slightly tilted away from him zone (imagine the zone is a rectangle piece of wood and the batter pushes the top of the piece away from him so that the top is farther away from him than the bottom. Also it should be a little wider in the middle than in the very edges (like an ellipse)
Of course, the pitcher has a say in this too. If a hitter adjusts pitchers will adjust too. There are some batters who can beat that a little like for example Brian Dozier who is very quick to the inside and thus can crowd the plate a little without opening apart but for most hitters that is not really true. So if a batter has a swing change and then struggles in the second half we should probably also look at the swing and pitch profile. Still, it is good for a hitter to match his swing rates and hot zones as even good pitchers will miss their target quite a few times. A batter not aware of his hot zones could leave serious potential on the table.
I also found one interesting thing. I looked at right-handed batters mostly in my analysis but also did a quick check on lefties. The lefties had a higher LA on inside pitches than the righties but a lower one than the righties on outside pitches? Why is that? handedness of pitchers faced maybe? I found indeed that righties facing opposite-handed pitchers indeed have a higher LA on inside pitches than against same-sided pitchers and against LHPs it was vice versa, so there seems to be an effect there.
And, lastly, the LA on offspeed pitches (10 degrees) was slightly lower than on fastballs (11 degrees). Surprisingly low breaking balls had a higher LA than low FBs but inside OS pitches where easier to lift.