Looking at pitch types and pitch receiving

The importance of a catcher receiving a pitch is not something that is new. Something that has been brought up lately though is how to exactly interpret the results. Jeff Sullivan of FanGraphs attempted to answer this question, and that article can be read here.

Following is some initial research into what we can think of as strike zones by pitch. PITCHf/x already provides pitch classification, and while the classification is imperfect, it’s gotten better and it’s close enough over big samples. We can tally up how many of each pitch type there were, and we can tally up how many of those pitches went for strikes. We can also tally up how many of those pitches were in the strike zone, and how many of those pitches resulted in one-of-zone swings. From here, we can end up with a number of expected strikes, which we can then compare to the number of actual strikes.

The sample included every pitch type (fastball, slider, change-up, etc.) that was thrown at least 1,000 times. Next, actual strikes were subtracted from expected strikes per 1,000 called strikes was found. Zero is average and if there are more strikes than expected then it means that the pitch receiving was easier, anything below zero is the opposite.

To nobody's surprise, fastballs, sinkers and cutters were the easiest to catch because they don't have as much movement. Pitches like knuckleballs and curveballs were much less favorable because they move so much more. In this study pitch counts were not taken into effect, so going forward that would be something interesting to look at.

Questions for the community:

1) How do you think pitch counts could affect expected and actual strikes?