The case against Zak Crawley

Running England’s first innings (NZ vs Eng, 29th Nov 2019) through my model told me that Zak Crawley had a median first innings score of 12. Absurdly low.

Rather than just spout that opinion in a tweet, I’ll walk you through how the model got there, and we’ll see if there are any gaps in logic. Have England made a terrible selection?

Zak Crawley’s County Cricket Record – Average 31

County Championship Division Two: 2017-18 – Runs 830. Dismissed 30 times. Average 27.7

County Championship Division One: 2019 – Runs 820. Dismissed 24 times. Average 34.2.

Second XI Cricket: 2016-18 – Runs 708. Dismissed 22 times. Average 32.2.

Redballdata.com Ratings – Expected D1 Average 30 – Rating those performances, and placing more weight towards recent performances, Crawley’s expected Division One average next year is 29.6.

Adjusting for Age – Expected D1 Average 30.4 – Zak Crawley is 21. He gets a c.3% boost to his expected average because his average is based on runs scored when he was 18/19/20.

Adjust for this innings – Expected Average 19.4 – A Test Match, away, against a strong New Zealand attack is much harder than a county game. That has a severe impact on average.

Run all that expected average of 19.4 through the model, and it predicted a median score of 12.0. What you would expect from a number eight batsman, not a specialist.

Gaps and biases

Let’s look at this from England’s point of view – why is Crawley in the team? I can think of three reasons:

  • He was in the squad, they didn’t really expect him to play. (That links to home advantage getting bigger as a series goes on: in this case it’s because injury means that a squad player, there to gain experience, gets drafted into the team.
  • England selectors use a different age curve and/or bias towards recent matches – bumping up Crawley’s expected average (along with every other young player).
  • Something in performance specific data (that doesn’t show up in averages) makes the England selectors think he’ll be especially suited to batting in New Zealand.

What happened?

Crawley made one run before Wagner got him. That additional innings has moved his expected average down a little more.

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