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Why Siri is Starting Tonight

Updated: Oct 18, 2021

I was asked in Twitter what I thought about Siri starting in CF tonight.

Two of the Astros media writers I respect the most relayed to Astros fans why Dusty said Siri was starting tonight.

Here at we will give you the reason the analytics department suggested Siri started tonight that is more comprehensive than what Dusty said.

First the main reason is that Siri is believed to have more range. I will come back and address this at some point but probably NOT before game 3.

For argument’s sake let’s say all three CFs were available although per Kaplan Meyers is not quite ready.

When the Astros are making this decision ask yourself about the Starting pitcher. What sort of pitches does he throw? Then ask who hits those kinds of pitches the best. Answer those two questions and you are likely to end up with the starting CF in this postseason.

Here is the data

Per Statcast, Rodriguez is a LHSP who throws 51% fastballs, 17% cutters, 8% Sliders, and 23% changeups.

Statcast then gives one the ability of each CF vs. those pitches (Cutters are included in the Fastball category). I have used xwOBA to help account for sample sizes we are using here. In short, Siri is expected to be a lot better at hitting the changeups.

As a result, Siri has an xwOBA of 0.425 (0.314 in average) vs. the normal repertoire the Rodriguez throws. This is 0.110 higher than McCormick. I suspect the gap is too large to be deemed a small sample size anomaly.

This are the numbers behind this decision. Enjoy watching Siri crush a changeup tonight.

If the starting pitcher is Fastball/ Slider RHSP- expect McCormick

If the starting pitcher is Fastball/ Slider LHSP- expect Meyers when healthy

If the starting pitcher throws a lot of off speed pitches like changeups- Expect Siri

What about the other three starting pitchers? I think McCormick (or Meyers) gets the nod if the gap is less than 0.7 xwOBA due to the small sample size for Siri.

Here is Game 1- Sale

If Siri did not have the healing hand and if he had more experience, he likely starts game 1.

Here is Game 2- Evoldi

McCormick might have gotten the start here with Chas being better than Meyers vs. RHP.

Here is Game 4- Pivetta

This may come down to how Siri does tonight in Game 3.

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