No more no less. It’s the magic number.
England’s red ball batting doesn’t have much going for it. But it has Joe Root.
Given that, it kinda makes sense for England to Put Root First when picking a team – then work out who should average 29 in the other six slots.
But word on the street is that Root wants to bat at three. At first glance that’s brave – Root’s data at face value says he’s best at four or five.
First, let’s bang some error bars* on those averages. Root at three averages 39 (+/- 11). At four that’s 51 (+/- 10). He’s probably better at four, but it’s possible the difference is just chance. Even after 53 innings at three, raw averages can’t prove to us that he’s a better three than four.
What about other batsmen? Is there a theme: is it easier to bat at second drop? There are fourteen batsmen who’ve batted more than 20 innings at both positions this century. Not that many people, so it’s open to interpretation. My reckoning: if you’re good at four you’ll be fine at three.

Going back to Root, is there something specific that means he’d struggle at three? Firstly, it’s worth noting that 60% of his dismissals at three were against India or Australia (at four, that figure is 48%), so there’s a bit of mitigation for his lower average one place up the order. Now, here’s Root’s record by over:

Joe Root is very good at batting. Averaging 40 in the first ten overs? He could be an opener. What makes that average even better is that if he’s batting early in the innings, chances are conditions are tough – because at least one wicket has already fallen.
So we’ve seen that Root should be fine at three. He’s good early in the innings. Others who’ve batted well at four have done fine at three. But is three his optimum position? No. He averages 44 against pace, 69 against spin. At four, he’ll get more spin**.
Does that mean that Root at three in the West Indies is a mistake? Well, he might be missing out on his favourite bowling: when West Indies play at home, spin makes up 23% of overs (England in England: 20%). My conclusion: if West Indies play a spinner, Root should bat at four. If West Indies are pace-heavy, then Root at three to try to meet the West Indies head-on is a gamble, but not an unreasonable one***.
*Error bars based on number of completed innings in each position.
**There’s a case for batting at five, but then you lose some runs due to being left not out. Plus England have plenty of lower-middle-order batsmen.
***Though, of course, nobody needs to know England’s batting order until the first wicket falls. Knowledge is power.