baseball win expectancy finder now has balls and strikes!

Here it is!

This wasn’t too much work, and like I mentioned last time it was nice to work on adding a new feature to something. Although I guess I did recreate the app’s shell with create-react-app, I didn’t port it to TypeScript 🙂

One annoying part is that there’s just not that much data so you can pretty easily get into situations where the stats are probably “wrong”. For example, in the top of the 8th inning, no outs or runners, home team up by 2, and a 2-0 count the home team has an 87.08% chance to win. But if the batter gets another ball to make the count 3-0 (good for the visiting team), now the home team has an 88.11% chance to win. I guess I should add a warning when the sample size gets too small or something. (although I don’t know what “too small” is)

I was a little worried that adding balls and strikes would bloat the size of the data files, which did happen. The worst-case is that it would increase the file size by 12x (4 choices for balls * 3 for strikes), but in practice it’s more like 9x. But it turns out that computers are fast so doing the lookups is only barely slower than before.

My original plan was to add the balls and strikes data to the mobile app (and make it an in-app purchase to unlock), but the increase in data size and corresponding memory usage make me less excited about it. Maybe at some point…

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