Attack Angle, Baseball’s Step-Child Metric

attack angle baseball

Today, we’re going to review the Attack Angle n baseball and the important role it plays in the swing path.  While everyone is focused on the Launch Angle, it often seems like Attack Angle is playing second fiddle.  Sometimes, the hardest part about Data Analytics is accepting what it tells you.  This article isn’t about what’s right or what’s wrong, or whether rotational is better than linear hitting (even though it is… Lol!).  Thanks to Rapsodo (post-contact) and Blast Motion (pre-contact) we can now sync up the results of a “hit” and reach some decent conclusions…

Attack Angle is the angle of the bat’s path, at impact, relative to the horizontal. A positive value indicates swinging up when bat meets the ball, and a negative value indicates swinging down, and zero is perfectly level.  Keep in mind at some point during the swing the bat hits a trough.  It’s all about when it reaches there… before, during or after contact is made.

There has been plenty of healthy discussion on this topic going back years, frankly it even continues today.  Positive angle guys are usually referred to as rotational hitters and flat to negative guys are called linear guys.  Although every single swing isn’t the same, if you take enough swings with a SwingTracker you can pretty much determine which one is you.

But, let’s talk about the dynamics of a baseball swing first.  Here is an image from a recent documentary (click here if you’d like to see it) on the baseball swing:

From the moment it’s released by the pitcher to the moment it makes contact with the bat, a 90-95 mph pitch takes approximately 400 ms to reach the batter.  That’s less than half a second.  If you zero in on the actual point of contact, it’s a fraction of that. We are talking about 7 ms, that’s 7 thousandths of a second!

So, if anyone is telling you they know everything about your swing by just looking at it, they are missing the point.  The whole thing happens way too fast for the human eye.  Don’t misunderstand me, you can observe a ton from watching a swing.  But, luckily, in present day, it can also be measured.

Now let’s consider the actual swing itself and the implications of different attack angles.  Here’s what we’re referring to when we’re talking about a Positive Attack Angle.

attack angle

On the other hand, here is a look at a Neutral Attack Angle.  Notice how the blue area shrinks.

Now let’s look at one with a Negative Attack Angle.  Notice how the blue area has shrunk even further.

attack angle

Making good contact is hard.  Making good contact with a Negative Attack Angle in baseball is even harder.  It doesn’t mean it’s not doable.  It’s just more difficult, and in a game of microseconds and tiny fractions of an inch, it can make a big difference.

Although there have been several write-ups that specify appropriate ranges of Attack Angles, we couldn’t find any supporting data or public research that supported any of them.  So, we started our own in-house review to determine optimal Attack Angles that would result in a desired set of outcomes.

The following was collected on a “pitch-by-pitch” basis during the course of several BP sessions (pitch speed 50-52 mph from approximately 45 ft).  The information covers 6 high school-level players and over 500 recorded data points.    As you can see their average AAs (bottom row) are quite varied, ranging from a -11 to a +10.  Before we get into the numbers, please note AAs aren’t like other metrics.  Looking at an average AA might be an interesting indicator but a player doesn’t have a “specific” Attack Angle.  They have a “range” with a relatively high standard of deviation.  Here is a quick summary profile for each player, listed from left to right by declining Exit Velo.

attack angle

Hitting has a lot of moving parts and it can be difficult reaching hard conclusions with a limited set of data among player’s with varied profiles.   So, we grouped the results to make them more relevant to each other.  First, we separated each player’s hits into 5 categories:

    • Attack Angle < 0 degrees
    • 0 =< AA < 5
    • 5 =< AA < 10
    • 10 =< AA < 15
    • AA >= 15

Second, since the objective is to hit a ball hard and far, we evaluated the results using a metric we call Well Hit Balls (WH Balls), defined as follows:

    • Balls hit at least with 90% of Peak Exit Velo
    • Launch Angle > 6 degrees (Rapsodo definition for a min. Low Line Drive)
    • Launch Angle < 24 degrees (Rapsodo definition for a max. High Line Drive)

Rapsodo generally selects their target #s based on information they have collected in the major leagues or nationwide.

The results were quite interesting.

The chart below provides a spread by “% of WH Balls” at different ranges of Attack Angles.  As an example, in the first column below, approximately 25% of balls hit with AA < 0 were WH Balls (as defined above).  Similarly, 35-40% of balls were WH Balls at an AA range of 5-15 degrees. Even though limited in scope with only 500 data points, the chart does show a bell curve peaking between 5-15 degrees.

In his article Optimizing the Swing (November 11, 2015), Dr. Alan Nathan (professor emeritus of physics at the University of Illinois, The Physics of Baseball) summarizes that although higher AAs could lead to higher distances, “another way to optimize the swing is for the attack angle to be essentially identical to the [pitch] descent angle, so that good contact still can result even if the timing is a little off”.  Given the 7 microseconds we referred to earlier at the point of contact, it certainly makes sense to place both the upward swing motion and the pitch descent angle (6-10 degrees depending the type of pitch) on similar planes.

So… what is a good attack angle in baseball?

If one considers 90% of Peak Exit Velo and Launch Angles between 6 and 24 degrees as optimal, then it certainly appears that Attack Angles between 5-15 degrees can lead to better overall results.

And now just for fun let’s check out 3 super imposed AAs at -13, Neutral and +17 (as measured by SwingTracker).  Foot plant is identical in all three swings.

By Bahram Shirazi (BSEE, MBA, Co-Owner RPP)

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