#Statcast

This is for the first two pitches, since 2016, RHP v RHH.

Go down the first column, and select the location region of your first pitch. Go across the row. That will tell you how often a pitch ended up in that region.

For example...

...when the first pitch was in region 32, the next pitch was in region 12 16.2% of the time (compared to an expected 5.3%).

How out of character is that? There were 210 pitches thrown to region 32, and so we'd expect to see 11 pitches in region 12. We actually saw 34.

Since one standard deviation is 1.5%, that gap of 16.2% minus 5.3% (or 10.9%) is a whopping 7.3 standard deviations.

Also note that throwing in region 22 on the first pitch also results in a much higher than expected in region 12.

In other words...

... if a first pitch is thrown high out of the strike zone, a non-random number of second pitches will target high in the strike zone.

If you see other patterns, feel free to note them in this thread.

For pitches thrown in the heart-of-the-plate, if you throw the first pitch in one region, and throw it again to the same region, that will happen randomly.

HOWEVER...

...for pitches thrown in all 8 regions of Shadow, all 8 regions of Chase, and in 7 of 8 regions of Waste, same region on 2nd pitch will happen a disproportionately higher number.

i.e.: a pitcher barely gets that location, or misses that location, will target that location again.