11 June 2008

Revisiting Liz's Debut: Fastball Release Point

Today I was going to write about the effect of manager ejections on team performance. Well, I have to cross reference a couple databases to do this and it has been a lot of manual work. I am nowhere near done answering this question in a meaningful way. What I will focus on today was something that was left out of the Liz study I put up last week. It has actually been eating on me and I have been trying to figure out how to show it. I have decided to just do it visually.

Strikes and Balls by Location

My first stab at determining how release point affects control was to use the arrival point as an indication of a ball or strike and compare that to the release point (graph to the right). What you see are two populations. The fastball group is located a little to the bottom and right of the ball group. The difference between the two is clear, but there is overlap. Primarily, the ball group has a lower density as well. A problem that may arise from this analysis is that a ball thrown to the dead center of the strike zone has a lot of room for error and still be considered an accurate pitch. Meanwhile, a pitch on the boundary of the strike zone will have less room for error before considered a poor pitch. This might be the cause for much of the overlap.

Strikes as Called and BABIP
To try to add some sort of qualitative nature to the issue here, I am going beyond pitch arrival location and focusing on the definition of an accurate pitch as one that results in a strike or a ball in play. What we see here is a lot more definition out of the strike release point. Anything over 6.3 feet looks like there is an issue with accuracy. You may notice the strike that has a release point north of 6.5. That one, as expected, resulted in a high fastball. It was chased and hit foul. You can see with this method that the overlap in balls vs strike is decreasing, but there still seems to be a mix in some locations of his release point.

Relating Vertical Release Point to High Fastballs
This is something we all know. Release the ball early and it rides high. One thing that is interesting is that all but five fastballs were within the horizontal bounds of the strike zone. This seems to suggest that Liz doesn't have a horizontal control issue, but that his main problem is not repeating the same release point. The graph shows his issue with high fastballs. He has a high release point. He'll need to be more disciplined in his mechanics to be more effective. As is, he will have difficulty keeping the ball down in the zone. You will notice that the overlap is far less on this graph.

This looks fixable.

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