First, let me start with an excuse: I’m not able to pull launch-angle data from Statcast and thus I’m only using the data from MLB.com as of May 16th 2017 this year. I’m currently learning R for doing better analysis, so if anyone knows how to get a complete LA leaderboard, please let me know.
We all know the the best LA for a HR is around 28 degrees and a HR is the best result in baseball. But still, when looking at the leaderboards, the best guys are all around 13-15 degrees. I looked at the top 10 in wRC+ to date this year and the average was 15.7 +/- 3.9. Looking at BABIP, the average was 13.6 +/- 4.0 (admittedly there is a lot of noise in BABIP at this point of the year) and in ISO the average was 16.4 +/- 4.9. That gives a small hint that BABIP peaks lower than ISO.
According to those data, BA peaks between 10 – 14 degrees, while slugging peaks much higher.
But there are also other factors why so far in MLB the best LA is around 15 degrees. According to Alan Nathan, the average fastball, depending on pitch height and velo, goes downward around 5 – 10 degrees.
That means the optimum swing for making contact goes upward 5 – 10 degrees. If you want more lift, you either need to hit under the ball more, which decreases EV, or you have to swing up more, but that means you are in the hitting zone for a shorter time, probably costing you some contact. Some sluggers will go above that, but then it comes at a cost.
And then there is the factor of EV sensitivity. Around 8 – 15 degrees the BABIP is not very sensitive to EV; most balls between 80 and 100 MPH will be hits. At 20 – 25 degrees that is very different; we are seeing that donut hole where you get the bloopers at 75 to low 80s and mostly outs mid 85s to low 90s, and then again HRs in the high 90s. Not every ball will be hit hard, so at lower LAs you get more out of your softly-hit balls.
And lastly, the LAs will be distributed on a Bell curve.
It doesn’t seem like players are able to consistently hit under the ball. That means if your average LA would be 28 degrees, basically half of your batted balls would be useless fly outs above 30 degrees, while if you peak at 15, most of your well-hit balls will fall in the useful 10 – 30 range. That also explains why EV peaks around 10 degrees — that is where the attack angle and exit angle match, and thus balls are hit on the screws while HRs tend to be a couple MPH slower than the hardest-hit balls (and many of the 110+ HRs are hit around 20-25 and not 30+).
Practically, that means that every player with a swing attack angle of below 10 degrees could benefit from swinging up more without any cost for consistency. Swinging up like 10 – 12 degrees means you get some lift and good contact. In fact, at plus 10 degrees, you are longer in the zone than at a completely level swing, plus your BABIP at 10 is better than at 0 degrees.
But above that, it gets more tricky, because slugging goes up but BABIP and contact can go down. For certain hitters with low contact and high EV profiles, it might make sense to swing up at up to plus 20 degrees to maximize whatever contact they get, but it will make the profile more extreme. The swing revolution is a good thing, but above 15 degrees many hitters might reach a point of diminishing returns when they try to elevate more.
Thus I think we will see more elevation of the launch angle. The average LA of MLB is now just below 13 degrees, which is well higher than the last two years (I think it used to be around 11 degrees), and I could see it go up to 15, but then I think the end of the line is reached. I think we are quite close to seeing the LA optimized in MLB. There always will be players who benefit from more, but there is a limit.
I think guys like Joey Gallo might benefit from going to 20+ but Trout and Harper are basically average in their LAs; they get enough elevated balls with their LA profile to hit 30+ homers and still have a high BABIP. I think the best all-around hitters/sluggers will stay between 13 and 15; it is only the below-10 guys that will slowly adapt or die. Guys like Ryan Schimpf will never become the norm. When many players were chopping wood, almost anyone could benefit from swinging up more, but a point of diminishing returns might be reached soon.