After initial apprehensions that spinners would have a hard time against T20 hitting, they have come a long way in the shortest format. Numerous spinners have established themselves as MVPs in varying conditions and in multiple leagues over the past two decades. The art of spin has evolved to keep up with the frenetic demands of T20: flat, quick wristspin has been in vogue in the past decade, and spinners today are using variations in speed and even bowling inswinging arm balls in the powerplay. As the table below shows, the economy rates of spinners are lower than those of pace bowlers in all major T20 competitions in the world over the past eight years, in the first 16 overs of T20 innings.
However, this dominance of spin has been on the wane in the IPL in recent times. Recently, I wrote along with Sidharth Monga about how spinners in the IPL are bowling slightly shorter and faster now. Flatter pitches, smaller boundaries, and aggressive hitting have squeezed spinners into bowling in the 5-7 metre length, restricting their attacking options. Less conducive surfaces and higher bowling speeds have translated to less deviation - the 2024 season of the IPL had the lowest average turn among the last seven editions.
With the lack of deception off the pitch, what options do spinners have to continue to evolve in T20 cricket? Enter overspin.
Overspin is often talked about in the context of Test cricket. Beating the batter in the air with subtle variations of flight and dip is an essential arrow in the Test spinner's quiver. Overspin also generally comes in handy on pitches in the southern hemisphere, which usually require the ball to be banged hard into the pitch to extract bounce and turn. Nathan Lyon's data shows that he mostly bowls with overspin instead of sidespin, whereas successful Indian spinners like R Ashwin and Ravindra Jadeja usually bowl with more sidespin, since Indian pitches offer turn without the need for overspin.
The rotations produced by overspin impart an extra downward force on the ball, in addition to the tug of gravity. This makes the path of the ball curve more sharply downwards, making it fall to the ground slightly earlier than the batter anticipates. The force that pushes the ball to dip drives it faster into the pitch, and produces some significant effects.
Consider Axar Patel and Kuldeep Yadav - the former releases from a much higher point, but Kuldeep has much more overspin on his deliveries. The dip on Kuldeep's deliveries makes them land on the pitch with the same downward speed as the much taller Axar's, due to the additional force provided by overspin.
Dip on the ball has multiple effects. It is well known that balls that dip bounce more because they land harder. Additionally, dip also gets the ball to spin more. The dipping ball makes contact with the surface for slightly longer, getting friction to act on it longer, and turning more as a result. Tracking data confirms this - for all countries, all speed ranges, all ranges of sidespin revolutions, more dip mostly translates to more turn on average in Tests.
More crucially, dip changes the length at which the ball pitches. Without any additional force from overspin, the ball falls to the ground due to gravity alone at an acceleration of 9.8 m/s2. Even an additional acceleration of 0.2 m/s2, which is less than 3% of the force of gravity, changes the pitching length by 20 centimetres on average. This change in length can mean the difference between a thick edge going to the ground and a thin edge going to the keeper. Dip is almost impossible to detect by the naked eye, since the ball is already curving downwards due to gravity, but its effects are multifarious and significant.
The graphic below shows an example of the shift in length, illustrating a delivery bowled by Ashwin to Ruturaj Gaikwad in this year's IPL. The blue track shows the actual path of the ball, while the grey shows where the ball would have landed without any dip. There is a 40-centimetre difference in where the ball pitches.
But why is overspin relevant to the shortest format?
It turns out that deliveries that dip provide an extra dimension of attack for spinners. Data shows that while deliveries with overspin yield similar or slightly lower economy rates than those without, they also yield a better bowling strike rate. This is true for both slow and fast spin, for both finger- and wristspinners, across the four-to-seven-metre "good" length for spin. The almost imperceptible change in length, the small amount of extra bounce, and the possibility of additional deviation, all combine to make dipping balls tougher to attack.
Curiously, in the IPL, the amount of turn does not increase with increasing dip, but goes up and down, in contrast to how it is in Test cricket. The reasons for this might have to do with the nature of white-ball pitches. The difference in bounce, however, is clearly shown by the data. The arrow plot below shows the average height of the ball when it reaches the stumps, for different lengths and speeds, comparing dipping deliveries to no-dip deliveries. For all speeds and lengths, dip causes the ball to bounce higher, with the difference being as large as 7cm at the stumps. This apparently small difference can translate a middled shot to an edge.
The greater bounce and the change in length translate to higher wicket-taking rates for balls with overspin. The arrow plot below shows the difference in the balls-per-wicket value for deliveries with dip versus those without. Across all speeds and lengths, dipping deliveries yield better results for wicket-taking.
The trend in Test cricket of increasing dip correlating with decreasing batting average was established in Hitting Against the Spin by Nathan Leamon and Ben Jones, and it is similar for T20.
The advantage of overspin is maintained over the years in the IPL. Even in the 2024 season, which was unprecedentedly tough on spinners, balls with dip returned a much better average than those without.
As Hitting Against the Spin explained, results against spin depend on the interception of the ball relative to the pitching point. For a favourable outcome, the batter needs to contact the ball either very close to pitching, to smother the turn, or well back in the crease, so they can watch the turn. My own research shows that intercepting the ball between 1.8 to 3.6 metres from pitching returns low averages - this is the zone in which the batter is neither forward nor back. Dip increases the chances of the ball beating the batter in flight and pitching in this zone, where the batter thinks they are stretched out to the pitch of the ball, but the ball lands shorter, increasing the chances of a mistimed shot.
This deception is beneficial for inducing false responses for both attacking and non-attacking shots. Using ESPNcricinfo's logging of shot data, we can investigate the impact of dip on the control percentage for different kinds of shots. As the plot below shows, the control reduces for all lengths for balls with dip on them. In the 4-5m length, the control on both attacking and non-attacking shots goes down by 8-9%. The difference reduces for shorter lengths, because the ball spends less time in the air, shrinking the window of deception. Nevertheless, the control does go down for all lengths. Against attacking shots, bowling with dip in the 5-6 metre length is the best option; batters are in control only 53% of the time against these deliveries.
Not only is this reduction of control true across lengths, it also holds when results are split by speed.
Spinners are often wary of bowling with overspin because the ball can "sit up" on flat pitches if they err short, making it arrive at a comfortable height for the pull shot. This is backed by the numbers. Deliveries with dip perform slightly better in terms of wicket-taking and control in the 6-7m length overall, but they are worse off when it comes to pull shots. Dipping and non-dipping deliveries offer the same control rate versus pulls in the 6-7m length (73%), while the former have a worse average (33 versus 27). Overspinning balls are still much better in the 5-6m length. These numbers indicate that bowlers need to be careful about going too short when bowling with overspin, while also being cognisant of their field sets in relation to possible attempts to pull the ball.
Overspin is mostly thought of as an attacking option in Test cricket, but its links to increased wicket-taking in T20 has not been discussed in cricket circles. The difficulty of seeing dip while watching the ball makes it tough to appreciate its presence or its impact.
Of course, dip is far from the only thing that brings wickets - bowling performance and strategy depend on a complex web of factors, and the best path is determined by the bowler on the ground, immersed in the game and aware of the conditions. Nevertheless, dip shows strong correlation with wicket-taking across lengths and speeds. In light of belligerent batters and placid pitches, the subtle variations dip induces in length and bounce make it a potent option for the modern spinner to attack more in a game where defending has become their mantra.