Picking our Pitcher Prince Charming

What can the hits in response to a pitcher tell us?

Pitchers can be categorized as “Fly” or “Ground” based on the tendencies of batters responding to their pitches.

Let’s Recruit…

Our team just lost their best ground pitcher, and now we need to find someone to replace him!

We should look at our candidates spray chart to figure out the outcomes of their pitches, but first let’s look at some examples.

Visual Representation of a “Ground” Pitcher

Visual Representation of a “Fly” Pitcher

Method

These graphs were created using ggspraychart, a function of the package baseballR.

Let’s use our ggplot knowledge to sign a new pitcher!

Syntax

The general syntax is very similar to other ggplot functions.

However, there are a few main differences…

Column names must be placed within quotations, global variables do not.

ggspraychart(data,
  x_value = "hc_x", y_value = "-hc_y",
  fill_value = NULL, fill_palette = NULL, fill_legend_title = NULL, 
  density = FALSE, bin_size = 15,
  point_alpha = 0.75, point_size = 2,
  frame = NULL
)

Defaults

Fill_value: Blue

Density: FALSE

Bins: 15 (Only applies if density = TRUE)

It is important to note that hc_y must be inverted due to the way statcast data interacts with ggspraychart.

How can these graphs help us?

Another Look

We can use the density parameter to better see the difference between our two example pitchers.

Fly-Ball or Ground-Ball?

Fly-Ball!

Our mystery pitcher is Shota Imanaga, a LHP for the Chicago Cubs. He is a great example of a fly-ball pitcher.

Do we sign him?

Unfortunately for Shota, we have too many fly ball pitchers already, so we will have to find another candidate for our team.

Good thing you are now equipped to find us a new ground pitcher!

Sources

ggspraychart: https://rdrr.io/github/Fackz/baseball/man/ggspraychart.html

Baseball Savant (statcast): https://baseballsavant.mlb.com/statcast_search