Kevin Pietersen’s ejection from the England cricket team is, on one level, extraordinary.

The greatest batting talent of a generation, as many think KP is, has been defenestrated for personal reasons, it seems. The need to rebuild, to move on from the Ashes debacle, meant a scapegoat was needed. KP was an easy target.

Perhaps all that is true. It’s also true that Pietersen’s genius and infuriating ability to get out stupidly has been known for years. Remember this headline: “Dumbslog Millionaire“? That was from 2009.

The truth is, Pietersen simply isn’t as important to England in the test set up as he once was, when it comes to the only thing that matters: scoring runs. In the meantime, captain Alastair Cook has grown in importance, and overtaken him.

To show this, I’ve taken each player and looked at their runs as a percentage of the England total in each innings. Forget averages – they are things like no-outs and by low run chases.

Now of course, that percentage fluctuates wildly. So to smooth it out, I’ve taken a rolling average of 10 innings.

Pietersen from the start of his career was very influential – he was regularly around 15 to 20 per cent of the innings. But that has waned, and apart from a brief spell around 2010-11, including the previous triumphant Ashes in Australia and the successful 2011 home series vs India, his percentage has tended to be below the 15 per cent mark for the second half of his career.

Cook, on the other hand, has seen his importance increase. His peaks over the 15 per cent mark have lasted longer and been more pronounced as his career has gone on, with a recent drop the only blip. His trajectory in terms of run percentage is on the up – KP’s is going down.

This is not something that people tend to measure – cricket watchers use averages, or talk about “important” innings. And those are fine – but they don’t show the relative run-accumulation within the team.

Pietersen is disposable because he isn’t indispensable any more. His runs aren’t any different when you add up the team total, even if gathered in a more exciting way. His sacking may be a huge story – but he won’t be missed nearly as much as some people think. As James Carville might say, “It’s the runs, stupid.”