After 81 Tests, Virat Kohli's Test average stood at an imposing 55.10. The 81st Test, versus South Africa in Pune in October 2019, was also the match in which he made his highest Test score - an unbeaten 254, his 26th Test century, which gave him a rate of 3.1 matches per hundred.
That, though, remains the only time his average has topped 55 at the end of a Test. In 18 matches since then, his numbers have slumped: the average has dropped to 30.26, and he has only managed one century, in the day-night Test against Bangladesh in November 2019. (Going by his rate of scoring hundreds till then, he should have had at least five in these 18 matches.) The slump has been so bad that Kohli's career average is now in danger of dropping below 50: if dismissed twice in his 100th Test, he needs to score at least 38 for his average to stay above 50 after this landmark game.
Comparing across eras
Kohli's average of 50.39 ranks 17th for batters after 99 matches. Topping the list are two Indian legends: Rahul Dravid averaged 58.16, and Sachin Tendulkar 57.99, going into their 100th Tests. Four other batting luminaries - Javed Miandad, Jacques Kallis, Ricky Ponting, and Kumar Sangakkara topped 55 going into their milestone match; it appeared Kohli would belong in that list too, till the form slump in the last couple of years.
While Kohli's average has dropped significantly, it is also important to keep in mind the fact that he has played in an era which is far more bowler-friendly than the period when some of his predecessors played. It is, therefore, only fair that each player's performances be measured against other batters who played in those matches, rather than across eras.
In the 99 Tests that Kohli has played, the other batters in the top seven positions have averaged just 33.82, which suggests that conditions were generally difficult for batting. The corresponding number in the 99 Tests that Dravid played is 39.11, which is almost 16% higher. Compare the ratios of those two averages, and there is little to choose between them: Kohli's is 1.49 times that of the other batters, while Dravid's is 1.487 times better.
Doing this exercise and comparing the ratios for all batters who scored at least 5000 runs in their first 99 Tests, Kohli jumps up to seventh place (compared to 17th in terms of averages). Leading the pack is Miandad: he averaged 56.76, while other batters in the top seven managed 35.36, a ratio of 1.605. Kallis and Viv Richards are close behind, while Brian Lara, Tendulkar and Sangakkara are the only others above Kohli. (To answer the inevitable question about the two modern giants, the ratio for Steven Smith is a staggering 1.766, while Kane Williamson's is 1.460.)
It is true that the average of other batters is also a function of the bowlers in the match, and to that extent, it depends on the bowling attack of the team that the batter belongs to. In Kohli's case, India's potent and deep bowling attacks in the last few years haven't given opposition batters much respite and opportunities for easy runs. However, the higher overall-batter averages for those who played largely in the 2000s - check out the numbers for Sangakkara, Ponting, Dravid, Tendulkar, Michael Clarke and AB de Villiers - points to a period when run-scoring was generally easier. Seen in that context, Kohli's career numbers, despite his recent lean spell, are better than they appear when seen in isolation.
The top scorer
Till his 84th Test, when Kohli scored his last Test hundred, he had made the most runs in a Test match 20 times, a record he shares with Lara for most such instances by a batter after exactly 84 Tests. Since then, he has achieved this only once, which means his aggregate-topping count in a match now stands at 21, second to Lara's 23 for any batter after 99 Tests.
At an innings level, Kohli has top-scored 41 times, which also puts him in the top 10 for a batter after exactly 99 Tests. Sunil Gavaskar and Lara are way ahead on 52, but the next-best drops to 44. After 84 Tests, Kohli had 38 top-scores - good enough for fifth place, after Gavaskar, Lara, Younis Khan and Wally Hammond - but since then the runs haven't been coming as easily. Can his 100th Test kickstart another prolific spell of batting form?