I have a theory that openers are better than middle order batsmen with the same average. If someone averages 35 against the new ball, that has to be better than averaging 35 against the third change bowler using a 60 over old lump of leather.
Here’s Michael Carberry’s take on the unique challenges of opening:
As openers, we don’t have the luxury of being able to come in against the old ball where it’s doing less. You see it on the first morning of a match. Everyone’s prodding the wicket. ‘Oh yeah, this looks a belter’. It’s never a belter when you’re facing the new ball. If the ball is going to do something, generally you’re the one who’s going to get it.
If Carberry is right, once openers see off the new ball, their expected runs for the rest of the innings should be higher than their career average – they’ve done the hard part.
How to prove it though? The proper way would be to show what various batsmen average at differing stages of their innings, against particular bowlers, against both old and new ball, and when the bowler is in their first, second, third spells. That’s not complicated, but would be time consuming, starting from a ball by ball database of Test Cricket. I haven’t done that. Instead, I’ve looked at what happens to a batsman’s average once they are “in”. Previous analysis tells me a batsman is fully in by the time they are 30 not out.
Analysis
- The benefit from “getting your eye in” is worth about five runs onto a player’s average (ie. if you average 40, by the time you get to 30* your expected average goes up to 45).
- Surprisingly, openers don’t get a further boost once they get to 30. This is odd – by the time an opener is on 30, 20 overs would have gone, the three best bowlers would have bowled six or seven overs and the ball would no longer be hooping round corners. I’ve definitely watched England play, rocking back and forth in my seat saying “if they can just get to 20 overs, see off the new ball, it will get easier. It’ll be all right”. Turns out that was piffle. It gets easier (c.12%), but it’s not a violent swing into the batsman’s favour.
- Weaker middle order batsmen get the biggest benefit from getting to 30. I think that’s because they really are the easiest times to bat – 40+ overs into the innings, tired bowlers, etc. In other words, these players aren’t becoming relatively better once they are in – they just tend to be building an innings as conditions become more favourable.
Conjecture
Put the above analysis together, and I’ll give you a second hypothesis – collapses in red ball Cricket are partly because lower middle order batsmen’s averages flatter them. A batsman that averages 30 can make hay in helpful conditions – yet they only average 30. That must mean that they average less than 30 in challenging conditions. Maybe when the going gets tough, the middle order will disproportionately get blown away. Unfortunately for me, that hypothesis doesn’t show up in the numbers. Yet.
Methodology
Since “Expected Innings Average” (EIA) is a non-standard metric, it’s worth explaining what it is and how I’ve derived it, else you’d have every reason to dismiss this as someone fitting the data to match their hypothesis.
EIA was calculated for every innings where a batsman scored over 30. Their runs in that innings (minus 30) were compared to their EIA to get a view of how their average (once they had got their eye in) compared to what one would expect from when they started their innings. Thus Benefit from getting eye in = Runs scored – EIA – 30.
To calculate EIA I started with the batsman’s career average. Then adjusted for the runs per wicket on that ground, then added or subtracted 8.5% depending on Home/Away. To adjust for not outs, I added the EIA to the not-out score.
For instance, when Virender Sehwag scored 319, his expected average was 49 (Career Average) * 1.2 (Ground adjustment for Chennai) * 1.17 (Innings Adjustment – for the 2nd innings of the match) * 1.085 (Playing at home) = 74. Conditions were favourable – but he still exceeded expectation by 245.
In case you aren’t a fan of the above, I also calculated the impact based on raw averages. It doesn’t reveal much. Just goes to show how important the context of an innings is: raw averages are just too simplistic.
Further reading
Michael Carberry’s recent interview in Wisden is linked here.
Here’s a proper statistician’s view of the early stages of a batsman’s innings – Bayesian survival analysis of batsmen in Test cricket. Note how low effective averages are when a player is on less than ten. A far more pronounced effect than I had expected.
Red Ball Data 