# What Factors into Distance?

Author: Jacob Hallowell, Penn State Data Science

When batting, a few main factors go into hitting the ball far. These factors include Launch Angle, Exit Velocity, Spin Rate, and Spin Direction. Using data acquired during batting practice with Hayden Stork, a Kernel’s Collegiate League (KCL) player, we are able to take all sorts of data and figure out how these factors affect the distance of a batted ball.

## Spin

The spin of the baseball off of the bat seems complicated but there are a few ways to simplify this concept. The first type of spin we want to look at is spin direction. Spin direction is as simple as it sounds, it is just the direction of the spinning baseball. However, there are a few types of spin that affect the flight of the ball. Topspin is when the ball is spinning downward, imagine a clock and imagine the ball spinning towards 6 o’clock. This topspin usually causes the ball to go down depending on how much the ball is actually spinning. The opposite of topspin is backspin, this would be a ball spinning towards 12 o’clock. Note that when a time is mentioned the ball doesn’t have to be spinning exactly towards that time, just somewhere in that similar direction. The backspin is the best type of spin when trying to hit the ball far because of how this spin “defies gravity.” Backspin allows the ball to “defy gravity” for a longer period of time, thus allowing the ball to rise more and giving it more time to travel. The last type of spin is sidespin, which is what causes slice and hooking on the baseball when it is squared up off the bat. Since these are usually well hit, but mistimed, the spin on the ball isn’t really enough to have a noticeable effect. During our session, Hayden Stork recorded a total of 35 hits. The breakdown of spin direction is as follows:

Type | Count |

Backspin | 22 |

Topspin | 10 |

Sidespin | 3 |

The other part of spin is the spin rate, which is the rotations per minute (RPM) the baseball has after it was hit. The more the ball spins, the more it affects the ball’s movement. If the ball is hit with high RPMs and backspin, the backspin will have more effect than it would if the ball was hit with low RPMs, assuming the other factors are held constant. However, there is a point where the RPMs can get too high and negatively affect the flight of the ball. The optimal spin is somewhere in between 1500 and 2000 RPMs, whereas anything above 3000 RPMs hurts the distance.

The graph above shows the relationship between the two areas of spin mentioned already. The x-axis is broken down into the three types of spin and the y-axis measures how many RPMs each type of spin has. As you can see, the balls hit with the backspin tended to have the highest amount of spin. There seem to be a few hits that had too much spin, but we can’t tell how it affected the distance quite yet. Sidespin had the lowest amount of spin, but it managed to land a hit in the optimal RPM zone. Sidespin and topspin clearly had the least amount of spin, which means the ball was very nicely squared up off the bat (sub-1000 RPMs).

**Launch Angle and Exit Velocity**

The other two factors that affect how far a batted ball travels are launch angle and exit velocity. Launch angle is the angle at which a baseball is hit off the bat. The graphic to the side gives us an illustration of what a launch angle looks like. Imagine that we are looking at a batted ball from the other batters box and that helps us decide what angle the ball was hit at. We clearly see the 0-degree line which would be somewhat of a line drive but end up hitting the ground. Then we see the 90 degrees and everything in between. Balls can also be hit at a negative launch angle where they shoot down off the bat.

The graph above shows the relationship between Launch Angle and Exit Velocity. The blue line is a computer-generated line of best fit, which is used to determine any trends that we might not be able to see. Clearly, there is a connection between Launch Angle and Exit Velocity, where it forms a bell curve of sorts. A higher launch angle usually has a lower exit velocity, which makes sense because the hitter is getting under the ball too much and cannot create a high exit velocity. The highest exit velocities seemed to be in the 0-20 degree range, which means the ball was barrelled up and hit hard.

**Creating Distance**

With all of our variables clearly defined, we are finally able to see how distance is created and what goes into hitting a baseball further. First, we know that we want backspin, to hit the ball hard, and at a launch angle that isn’t too low or too high. However, how much do these things affect distance? Through a series of graphs, we are able to tell how important each factor is in making the ball go further.

The graph above breaks down three variables: distance, spin, and spin type. As we can see, Distance and spin aren’t very closely related, but spin type seems to have something to do with distance. It looks like sidespin traveled the least amount of distance out of the three spins, which makes sense because it is hard to get sidespin on a well-hit ball. Topspin also had a lot of lower distances, with only one hit above 150ft, which also makes sense because of how it spirals downward. Thus leaving the backspin with the most distance. If spin were related to distance, there would be a clear pattern in the graph. So, seeing that there is no pattern to this graph, it is safe to say there is no direct correlation between spin rate and distance, whereas spin type and distance are definitely correlated.

Next, we want to break down launch angle and exit velocity vs distance. These are very simple graphs because they only show two variables lined up on the axes. The first graph represents exit velocity vs distance.

This graph shows some sort of connection between exit velocity and distance. It gradually rises, so there is some sort of correlation that as exit velocity rises, so does distance.

Another thing to look at is launch angle vs distance. This time we have distance on the y-axis, so the graph is easier to read and notice a pattern. Sure enough, there is a very clear pattern to this graph, and it forms a sort of bell curve. So, there is a clear optimal zone for launch angle if you want to hit the ball as far as possible. This zone seems to be at its peak around the 20-30 degree mark.

Overall, there are a couple of things you want when trying to hit the ball far. It is hard to rank the four categories we mentioned earlier because all of them are needed to hit the ball far. For example, launch angle means very little without exit velocity and vice versa. Backspin is very important, but a high amount of RPMs on the ball could negatively affect the distance. When you break it down, hitting is an art and there are a lot of things that go into it, even if you aren’t thinking about it.

*Acknowledgements*

*Kernelytics Team: Cade, Christian, Clark, Ian, Jeff, Matt, Robert**Baseball Analytics Mentor: Jarrett Rodgers**All KCL players that participated**The Corn Crib and Play9 for getting us access to a Rapsodo Unit*