Cubs Quick Hits: When Pitching Stats Become Meaningful
Eno Sarris of FanGraphs, whose work you should be reading regularly, just published a post on the point at which pitching stats are relevant.
In short, Sarris — along with Brian Cartwright — posits that you don’t need a large sample size to draw meaningful conclusions. For example, sinker velocity stabilizes at just 10 pitches. That means only an inning of work or so provides enough data for us to believe that future pitches will yield similar results.
| Stat | Denominator | Stable At |
|---|---|---|
| Sinker Velocity | Sinkers | 10 |
| Sinker Horizontal Move | Sinkers | 10 |
| Sinker Vertical Move | Sinkers | 10 |
| Changeup Velocity | Changeups | 10 |
| Changeup Horizontal Move | Changeups | 10 |
| Changeup Vertical Move | Changeups | 10 |
| Contact% | Swings | 40 |
| Changeup Contact% | Changeup swings | 50 |
| Sinker Contact% | Sinker swings | 70 |
| O-Zone Swing% | Pitches outside of zone | 120 |
| First Strike | First pitches | 250 |
| Zone% | Pitches | 330 |
So much for all those “small sample size” caveats, huh?
I highly recommend you to read the rest of Sarris’s post, in which he says, “…Jake Arrieta is down almost three ticks, that stuff is meaningful.”