A tale of batting averages and the things they don't tell us

I've just started a new weekly podcast where I pop over to Spotify Greenroom and take questions from folks. We do it every Friday at 1330BST. And if you want to come chat, you can download the app, follow me there and ask some questions.

This week I had one about whether Shreyas Iyer should replace Ajinkya Rahane in the Test team. In fact, it was a more nuanced question than that. It was whether Rahane was ruining the chance for Iyer to develop in Test cricket. And one reason for the question was that Iyer is now almost 27, and time is running out.

I'm not sure I believe 27 is that old. But I do worry about batters who play too much cricket at the first-class level before a debut if they're good from the start. Let's call this the Graeme Hick prison and leave it there.

I handled the Iyer question as best as I could in real-time, but I couldn't get it out of my head.

Let's start with the obvious, Iyer is an incredible talent. In 54 first-class matches, he has nearly 5000 runs, is averaging 52 and striking at over 80. Those all sound like made-up numbers. And it's hard to argue that he doesn't deserve a chance.

And there are many fans - as I find out nearly every AMA - who question everything about Ajinkya Rahane. There are a few reasons; one is that his average is "only" 41 in Tests. Another is that he goes out the wrong way. I've talked about this a lot; if you're dismissed LBW or caught behind, people see that as an honourable dismissal. But get caught from Neil Wagner's legside trap or slicing a full toss to cover, and he's suddenly not good.

But let's get to Rahane in a minute. Iyer's basic numbers are incredible, and I think he's a magnificent talent, quite obviously. Yet it's also worth inspecting him.

One that was mentioned in the chat is that he bats five domestically. It's interesting how people believe that - I have heard that before. And people in cricket often discount batters who have huge numbers from batting down the order. There is a lot wrong with this thinking, it's reductionist, and while it's true that it's easier to bat in first class cricket the further you are from the new ball, it's also true that there's a lot more to it than that. But it doesn't matter, as Iyer actually bats at number three, so no one can use their cricket bias against him.

Iyer averages 57 at three and 43 at four. Not sure that means he needs to bat higher, but it is interesting considering it's almost always Rahane he is said to replace, not Pujara. But it means he bats high enough to get noticed and respected. Even if that's a largely rubbish metric for checking talent.

But slicing his career up he's played a lot for Mumbai and India A, and that's about all. For Mumbai, he averages 54 and when he's with India A, it's 46. That's a fair drop, especially considering his best score is 202 not out, and that was for India A.

It's worth mentioning that 202*, as it was against Australia. Not the A team, but the actual team. However, the new ball attack didn't include Cummins, Starc or Hazlewood; it was Jackson Bird and Mitch Marsh. But Steve O'Keefe - who had a pretty wonderful tour of India - and Nathan Lyon played. So the innings can't be discarded. Also, no one else scored over 74 for his team.

But, the innings was in Mumbai. And this is the most interesting thing for Iyer.

This one was Brabourne, but he's also done well at Bandra Kurla and Wankhede. In all he's played 15 matches in Mumbai, and averages 69. In the rest of first class cricket not in Mumbai, he averages 43. It's not terrible, but it makes his overall record look different, doesn't it?

He has only played three first-class matches outside Asia, where he averages 26. But we can't take that too seriously.

However, you know who has played a lot of cricket outside Asia, Ajinkya Rahane. And not just in first-class, but Tests. Way more than half his matches are away from home. And in those, he averages 44. That's a remarkable record. There aren't many batters who are better away from home, and Rahane is almost eight runs better. That is so handy. Most teams can find players who do well on local pitches; finding someone who can make consistent Test runs when travelling is really tough to find.

And ofcourse Rahane has other skills, the ability to give strategic advice, and he's an incredible slip fielder to spin. But even if he wasn't those two things, let's think about those averages.

Iyer averages 43 away from Mumbai, Rahane averages 44 away from India.

That doesn't mean that Iyer isn't more talented than Rahane, but it puts Iyer's record into perspective.

Also, I checked Rahane's average for Mumbai. It's 60. Which if nothing else, might suggest Iyer's talent is comparable. But Rahane still has him covered by six runs there, even before you factor in the years of experience and safe hands.

Rahane's inability to score at home remains bizarre. If he cashed in like many of his other Indian batter friends, his numbers would look amazing, and few people would call for his head.

But I think this shows us something else, the way we as fans get sucked in by the magic of the 50 average. Iyer is still a magnificent prospect, but Rahane's 41 Test average looks worse than it probably is.

Not to mention that Iyer is the shiny new thing while Rahane goes out in unfashionable ways. If there is really a deeper truth to this,  it;s that while averages are still a very good metric for first-class and Test players, there’s a lot that can be found beneath them.

Also, if you are an Indian player, and you are anything less than perfect someone will be trying to replace you.