There's a joke going around that the L in the IPL stands for "legspinners". Not just in the IPL, legspin is the most valuable currency going around in T20 cricket across the world, international or otherwise. If you're following the T20 leagues, you already know about the contribution and influence of legspinners. Numbers suggest that in T20 cricket, it isn't so much about the quality of legspinners as their basic ability to take the ball away from the batsman.

Here are the T20 career numbers for some of the world's leading legspinners.

Bowlers Economy rate Strike rate
 Amit Mishra  7  17.7
 Imran Tahir  6.8  18
 Anil Kumble  6.69  21.8
 Shane Warne  7.22  22.1
 Karn Sharma  7.39  20.6
 Adam Zampa  7.13  21.1
 Shahid Afridi  6.66  19.8
 Pravin Tambe  6.96  18.9
 Samuel Badree  5.41  21

All the bowlers above concede around seven runs an over and take a wicket or two in each four-over spell. Bowling in T20 cricket is about these two aspects - economy and strike rate. If you concede on an average around seven runs an over and take 1.2 wickets in 24 balls, you'll be rated a successful T20 bowler. These legspinners are doing just that. So, what makes legspinners succeed in T20 cricket?

Forcing batsmen out of their comfort zone
The shortest format of the game demands a lot of six-hitting, especially against spinners. Batsmen tend to dominate with their bottom hand and go through the leg side a lot more in T20 than in other formats. Since the World T20 this year, 65% of all sixes have been hit between long-on and front of square leg. Legspinners, who turn the ball away, make it tougher for the batsman to target this preferred area while going aerial. Since legspinners can legitimately take the ball away from both left- and right-handers, they force batsmen to find different ways to score.

Many captains keep left-arm spinners away from left-hand batsmen and offspinners from right-hand batsmen, but there's no such compulsion with legspinners. Big hitters rely on having a stable base, which means most stay put in the crease while hitting the long ball. While that approach works perfectly against offspinners because the ball comes in after pitching, it's not as easy when the ball is going away. Legspinners force the batsmen to use their feet to get closer to the ball and cover the spin. This is something not all modern batsmen are equipped to do.

Lower trajectory by default
Offspinners are always advised to have a short delivery stride, for they must stand tall at the time of release, with the bowling arm close to the ear. Since fingerspinners generally get less turn than wristspinners, they need to look to get the extra bounce. While bounce works well in the longer formats, it's detrimental in T20 because it allows the batsman to get under the ball and hit it in the air.

This is why we often find offspinners bowling with a roundarm action in T20, but that leads to them undercutting the ball and compromising spin off the surface. Once again, they end up making it easier for the batsmen.

Legspinners, on the other hand, have a long delivery stride by default and are also advised to bowl slightly roundarm to extract sidespin. The long delivery stride and the roundarm action lower the point of release, so they extract less bounce by default. That explains they tend to get away with bowling a little short too: there may not often be enough bounce for the batsman to get under the ball and go aerial.

In T20 cricket, spinners are taught to ensure that the ball never goes above the batsman's eyeline, because doing so allows the batsman to use his feet. While offspinners have to modify their actions to suit this particular demand, most legspinners are able to achieve this without tinkering with their original action.

Reading the ball from the hand is no longer in vogue
While T20 has certainly enhanced hitting ability, batsmen no longer seem to read the spin from the hand, and this has contributed to legspinners doing exceedingly well in T20.

Whenever you see a batsman going backwards to a reasonably full ball, you know that he hasn't watched the release closely and is unsure about which way the ball is likely to turn, which is why he has gone back, hoping to read the spin off the pitch. Reading spin off the pitch is a dangerous gambit, even when you're trying to defend, because there's very little time to adjust after the ball has pitched. So imagine how difficult it would be to choose or change an attacking shot depending on which way the ball has spun after pitching.

Going down the pitch and using the momentum of the body to clear the fence is a tried and tested way of attacking spinners, but that's possible only when you're certain about the spin, which happens only if you have watched the release closely. Since most batsmen aren't watching the hand at the time of release, they tend to avoid using their feet, and when they do, they are often beaten off the pitch.

Aakash Chopra is the author of three books, the latest of which is The Insider: Decoding the craft of cricket. @cricketaakash