India have just lost an ODI series in what can objectively be termed pretty extreme conditions. In no bilateral ODI series of three matches or fewer have so many wickets fallen to spin: 43 out of 54, which also includes three run-outs, leaving just eight for the quicks. Only once has more spin been employed in a three-match ODI series, back in 1997-98 when Zimbabwe toured Sri Lanka.
Having not won an ODI series against India since 1997, having lost the T20Is 3-0, Sri Lanka took a calculated risk. They were missing a handful of their first-choice quicks because of injuries, and did what they needed to do to make the ODIs competitive. They prepared pitches that would offer appreciable turn and natural variation to spin bowlers, and enjoyed a bit of luck in winning all three tosses and getting the best of batting conditions.
At any other venue, batting first in a day-night game is fraught with danger because dew can handicap spinners in the evening, but this is where the R Premedasa Stadium's history is worth knowing. There was a time not long ago when it used to be impossible to chase in day-night matches at this venue, dew or no dew. The stadium was built in low-lying marshy land, and the underlying moisture would come up to the surface of the pitch in the evening, giving fast bowlers a significant advantage.
In the decade before the 2011 World Cup, 32 of the 45 day-night matches at the Premadasa were won by sides winning the toss. Before that World Cup, though, the playing surface was raised by three-and-a-half feet, and it did the trick. Sri Lanka chased successfully in their quarter-final and semi-final. The relevance of this history lesson now is that if you make a dry track, you need not worry about it getting better to bat on with the evening moisture or dew playing a significant role.
Sri Lanka got their strategy right, had the rub of the green, and bowled superbly despite India getting off to three quick starts, thanks almost exclusively to Rohit Sharma, and defeated a side that had gone unbeaten through last year's World Cup before the final, and one that had been dominating Sri Lanka in recent years.
We don't have the HawkEye data to back it up, but the commentators suggested that it turned more and more as the matches progressed, and it does bear out in the batters' output against spin. However, there seems to have been a clear difference between the sides in terms of approach. Sri Lanka seemed to be more conservative against spin while India looked to attack them more. It gave India a slightly better scoring rate but hurt them significantly with the wickets lost.
In his analysis of his team's batting, Rohit made an interesting point. He said India didn't play the sweep shot as often or as well as Sri Lanka did. His observation was spot-on on both counts. Not only did Sri Lanka employ the various varieties of sweep more often, they also fared much better when they did. There is a good reason why India didn't try it as often: they a lost a wicket on every fifth attempt.
If played well, the sweep brings more than just the immediate runs scored. It makes the fielding captain defend more areas of the field, opening up spaces elsewhere. That is particularly true if you play the reverse-sweep well. The threat of the reverse-sweep can force captains to deploy a deep point and open up the extra-cover region. It also messes with the spinners' length.
Historically, India haven't been the greatest of sweepers. Improving on all kinds of sweep was the endeavour when Rahul Dravid and Rohit led the side. As with all things, there is a delicate balance: you improve on this new shot but don't disregard your traditional strength, which is to get to the pitch of the ball or go right back. That India weren't excellent on that front in this series is something that will concern them, especially Virat Kohli, who was twice caught on the front foot without getting anywhere close to the ball, giving him little chance to recover against the ball that didn't turn.
These numbers don't automatically make India a poor team against spin. Over the same period since 2019, India have the best average against spin in ODIs and only England and South Africa have scored quicker than them. Nor do those numbers necessarily make them the best batting unit against spin. It probably suggests that when there is appreciable assistance for spinners, India perhaps don't do enough to force the opposition bowlers out of their comfort zones. This is something Rohit has said India will continue to work on.
The one other thing that stood about India's series loss was their less-than-optimal use of bowling resources. Even that possibly came down to their obsession with keeping a seam-bowling allrounder ready should Hardik Pandya not be available. That is possibly why they persisted with Shivam Dube through the series when the conditions called for a spin-bowling allrounder in Riyan Parag. Sri Lanka's spinners, then, not only fared better but also bowled a lot more than India's: 81.1% of their team's overs to India's 65.3. Some of this might have been down to there being more assistance for spinners in the second innings but the make-up of India's XI perhaps also had something to do with their willingness to pay a short-term price for what they believe is a long-term pursuit.