@MajorLeagueUmp or @[TeamNickname]Ump<p>You're watching a baseball game. The pitcher throws a pitch right down the middle of the plate, but the umpire calls it a ball. Was it really a bad call or did you just have a bad angle.<p>@MajorLeagueUmp or @[TeamNickname]Ump tweets bad ball and strike calls in realtime and includes:<p><pre><code> - A picture of the pitch location
- Percentage of the time a pitch in that location is called a strike
- How far the pitch was from the edge of the *real life* strike zone
</code></pre>
On TV, FoxTrax will show you where the pitch went relative to the rulebook strike zone, but it won't tell you if pitches in that location are typically called strikes. I found this frustrating because any baseball fan knows that the real strike zone is different than the rule book zone.<p>To find the actual zone I:<p><pre><code> 1. Downloaded Pitch F/X data from the last four years.
2. Built a fine-grain heat-map of called-strike percentages.
3. Applied some gaussian filters.
4. Converted the heat-map into perimeters
(inside this line it is a strike 78% of the time, etc).
Polar coordinates finally turned out to be good for something.
</code></pre>
The tweets are updated by:<p><pre><code> 1. Nodejs server on heroku that monitors Pitch F/X data in real-time.
2. Each pitch is stored in Firebase.
3. Compare the pitches to the actual zone from above.
4. If the call was really bad, generate an SVG and tweet.
</code></pre>
I've been researching the strike zone on and off for the last 5 years. At first, I wanted to answer two questions.<p><pre><code> 1. Where are balls and strikes actually called?
2. How consistent are umpires in making those calls?
</code></pre>
Some quick answers:<p><pre><code> 1. They widen the plate a tad.
2. They really round off the corners.
The strike zone is closer to a circle than a square.
3. Left handed hitters face a much larger strike zone
that extends well off the outside of the plate.
4. They are actually pretty consistent, but not perfect.</code></pre>
is the 3-d strike zone incorporated into these calculations? i know the strike zone has width, in addition to length,height. so when you say the strike zone is more of a circle, i would contend it's a horizontal cylinder.