The thing about heat maps is that one size does not always fit all. Depending on the density of pitches and how many pitches are thrown, it’s not always a clear cut case how to display the data. Sometimes you want the points bigger, sometimes you want the “intensity” of each point to be more and sometimes you really want a different color scheme. For instance here’s the same chart, but with the settings changed.
And here is a third chart, with the settings changed one more time, where the points are made smaller but very intense in monochrome.
There’s a lot to play around with here and a lot of options to try and get the best picture possible.