Why the perfect launch angle is 15 degrees and not 30

You might be conflating launch angle (path of the struck ball) with bat swing angle (ie Zepp 'attack angle' or angle of the bat).

The 'perfect' launch angle is still 30 deg.  As you point out, nobody typically swings with 30 deg bat angle to generate a 30 deg launch angle.

Balls struck at 30 deg launch angles are then obviously typically hit with 15-20 deg attack angle, and therefore is almost always in reality undercut with backspin. (This point is missing from everyone's analysis)

Almost everyone in MLB undercuts because the bat head drops below the pitch angle.

The bathead drops below the pitch but not really below the pitch plane. The ideal ball is slightly undercut but the graph shows there are just as many hit over than hit under balls.

The data I cited were launch angles and not attack angles (which are probably like 8 to 15 degrees) if guys like trout could consistently undercut the ball their launch angle would higher than their attack angle but it isn't.

The ball is still hit below center but only in relation to the ground and not to the pitch plane.

Of course trouts homers are still hit under but it seems like they are more of a byproduct.

Dominik85 posted:

The bathead drops below the pitch but not really below the pitch plane.

The avg pitch plane for fastballs is approx 5-7 deg.  (It could be 6-10 using an L screen) The avg swing plane is usually 10deg. Most bat heads drop below the pitch plane.

Note: This is also why one should never use a Zip-N-Hit or use the 2 tee drill.

http://m.mlb.com/news/article/...-for-5-against-cubs/

Zack Cozart disagrees with the optimal launch angle.

On a serious note good stuff. Technology is has been taking the art of hitting to a new level.  Hopefully the practical teaching methods of how to use this data can catch up.

Great post and really good follow-up by Sultan. I love this stuff.  It's worth noting that average swing angle you reference is for all swings on balls in play regardless of pitch type or ball exit speed. To me, ball exit speed after contact needs to be factored into any construct of "perfect" launch angle.  

Instead, I like a chart I read this weekend which suggested, like Sultan suggests, that the perfect launch angle with most bang per swing, is closer to 30 degrees. I think the data broke along lines of:  for balls hit at 90+ MPH and a launch angle of 30 degree, more than 95 percent went for extra base hits. 65 percent of those were homeruns, with a lower percentage going for triples and doubles. Interestingly, fewer than 5 percent were singles!

At any rate, thanks for posting.

Cozarts average LA this year is 13 degrees.

I'm not saying 15 degrees is most productive, it is just best for the overall profile if the average is around that.

This might just be me, but I don't think any MLB player consciously goes through a swing trying to produce a 30 degree launch angle on a pitch. It seems more of a by product of a bat angle, or how much you swing up at the baseball. The thing that seems to be controllable is bat angle and depending on how good your hand eye coordination is, will come out a certain launch angle.  I don't necessarily think Cozart has pefect hand eye coordination because his bat angle seems to line up with launch angle (-8 to -15 BA, compared to a 13 LA), compared to maybe a Donaldson, with a 35 LA with the same -8 to -15 BA. This probably has to do more with mentality in knowing how much power you have and where to aim to hit the baseball. A common thing throughout all levels of baseball is knowing what type of hitter you are, as Jean segura (leading the MLB in average) is probably going to aim higher on the baseball than a Donaldson. I would argue that almost every player in the pros swing at an upward plane for best results with maybe the exception of Mookie Betts.

A lot depends on exit speed when analyzing launch angles. As you can see by the following chart, for example, launch angles of 25 degrees resulted in a .679 batting average if the batter was able to back it up with a 100 mph exit velocity, but dipped to .114 when only swinging hard enough to affect 90 mph. But, you can see here that you're correct in one respect, a 15 degree launch angle provides very good results across a range of exit velocities.

What's the average FB angle coming from the mound?

https://www.wsj.com/articles/h...;utm_campaign=buffer

“I didn’t even finish college, and I can tell you if you hit a ball 95 miles-per-hour that’s over 25 degrees, it’s going to be a home run,” Zimmerman said in a recent interview in the home clubhouse here at Nationals Park. “That’s the easy part.”