Perhaps average alone isn’t enough in determining a great player, it is the single match-changing innings that define a player; isolate him or her from players that may consistently contribute but don’t force themselves and their team into a winning position. The big hundreds that take the game away from the opposition.

When writing this, Root has 45 fifties and 16 test centuries. Undoubtedly impressive, but raises one of his biggest problems: conversion. This really tells us that he has 61 times made it past 50, but only 16 of those times has he converted those into a century. In contrast, Kohli has made a 50+ score fewer times at 49 but leads Root with 27 of those being centuries.

This plot shows that Root struggles to keep up with the great conversion rates of the other ‘Big 4’. Kohli and Smith are improving their conversion rates, converting fifties to hundreds ~50% of the time.

Lack of converting fifties to hundreds is often a topic of conversation with Root.

The rate of conversion may not seem important as long as runs are being scored. The below plot shows that Root has got to 50 plenty of times but it is typically centuries that win matches for your side when batting, not 60s and 70s.

This is a large contributing factor to his average drop. Without the hundreds to balance the inevitable low scores of test cricket, we have seen Root’s average fall whereas the now ‘Big 3’ have been able to produce big runs when they’ve found themselves ‘in’ and past the half century mark.

Root has produced more than enough chances for hundreds.

If Joe had continued the conversion rate that we saw in his early career, or was matching that of the other top batsmen, then he would most definitely be amongst those top 3 in the rankings and possibly in the view for being the world’s best batsman, England would greatly benefit from having a top batsman sure up the middle order taking pressure off a new opening pair and unsettled lower order and we wouldn’t be debating his position as captain. It could be that captaincy pressure or the lack of runs present elsewhere in the team causing the jitters between 50–80, or a combination of both.

However, if we take a look at Smith, Kohli and Williamson and their run production while captaining, we can see that the gulf reflected in the rankings really has formed. Smith’s record is, quite frankly, ridiculously impressive and one can only imagine what it would be had he not been banned for over a year. Williamson and Kohli have made steady progress while Root has almost exclusively declined and fallen away since becoming captain.