To york or not to york in T20?

On YouTube there is grainy footage of a tussle between Waqar Younis and Brian Lara in a Rawalpindi Test, in 1997. Lara scythes Younis for consecutive fours, regally swatting the ball through the off side. Then, Younis curves a delivery through Lara, which bounces just before eviscerating his leg stump. Lara is left with his feet dragged outside leg stump, his hands on the ground outside off, trying to stop himself from falling face down into the turf. What's left of his stumps is in between.

Such are the disorientating effects of a brilliant yorker: a delivery that can render the pitch, the conditions and even the batsmen themselves irrelevant, subservient to the bowler's will.

The effects can be just as devastating in the harum-scarum world of T20 as in Tests. Consider Jofra Archer, who has excelled in the Bangladesh Premier League, the Big Bash, the Pakistan Super League and now the IPL in the last six months. For all his pace, his potent bouncer, well concealed slower balls and sheer big-match chutzpah, Archer's yorker is the single most important factor underpinning his T20 rise. Archer has bowled 61 yorkers in his T20 career; these deliveries have cost a total of 38 runs, while taking nine wickets at an average of just 4.22.

The trouble is, producing yorkers with anything like this reliability is astonishingly difficult. In T20, the yorker is a fast bowler's death-or-glory ball. When done well, no ball is more effective. Yet when bowlers err and deliver a yorker a couple of inches too full or too short, they can reliably expect the ball to hurtle straight back past them and not stop until it is in the stands.

Chris Woakes, one of the leading death bowlers in ODI cricket and also a regular IPL death bowler for Royal Challengers Bangalore, estimates that only about 50% of attempted yorkers are successful. It may well be less than that; Lasith Malinga, widely considered the greatest practitioner of the T20 age, actually bowls over three full tosses for every two yorkers he manages to deliver in T20, according to ESPNcricinfo's data. Even the brilliant Archer has bowled 50 full tosses alongside 61 yorkers; these have been hit for only 12.24 an over, and have only claimed two wickets at 51 apiece.

Malinga has taken 17 wickets with yorkers since 2014; he averages 11.29 when he bowls a yorker, with an economy of 5.49. Even if they are a little less extraordinary than Archer's, these are brilliant numbers. Yet to understand why Malinga bowls yorkers 9% of the time (effectively, two every four-over spell in T20, and twice as many as Dwayne Bravo, the most prolific bowler at the death in T20 history) as important is understanding his record when bowling full tosses. Malinga only concedes 8.52 an over bowling full tosses - still well under the average scoring rate in the death overs - which means that he needs to be less fearful than others of slightly overpitching his yorkers.

"Bowlers with slingy actions bowl them better due to their low arm, and there is less possibility of getting it wrong due to trajectory," says Steffan Jones, a fast-bowling consultant for teams around the world. Jasprit Bumrah and Chris Jordan, two other bowlers who bowl from low trajectories, also have terrific records with their yorkers.

In Test cricket, where wickets are worth more and runs are less costly, a yorker is comparatively more attractive. Fast bowlers here can also use the classic bouncer-yorker combination: driving batsmen onto the back foot with a series of short balls and then unfurling the yorker. The trick was especially effective before 1991, when bowlers could bowl an unlimited number of bouncers an over in Tests; the West Indies giant fast bowler Joel Garner was one of the greatest exponents. And yet in Tests, yorkers are deployed less frequently than in the other two formats: a testament both to how difficult the balls are to bowl, and the fact that the delivery is most potent as a surprise - except, perhaps, against the tail, when tailenders might expect bowlers like Waqar and Dale Steyn to unfurl yorkers but can seldom do much about it.

In T20, quick bowlers are only allowed to bowl one bouncer an over (it is two in one-day internationals) - so, effectively they can't use the bouncer-yorker combination in the same way as in Tests.

More importantly, in T20 the margin for error is infinitesimal - and smaller than for other comparable deliveries. "Unlike a slower ball, the yorker can only be bowled perfectly into the blockhole," says Ian Pont, a fast-bowling coach. "If the bowler misses his spot it can get hit for six - whereas the slower ball can be bowled 'poorly' but still be effective."

So the skills needed for a yorker are more precise - and, Pont believes, it is simply more difficult to bowl well. "Bowlers are less skilled in yorker bowling than they are slower balls and change-ups of speed. It is far easier to slip in a cutter or roller of the fingers than to master the discipline of hitting a yorker length."

Even in Test cricket, the very best bowlers can't reliably hit the same spot anything like every time, as Jarrod Kimber explained last year.

"The yorker is a very high-risk ball," Dirk Nannes, the former T20 bowler has said. "If you stuff it up by six inches then it's a four or a six. So unless you are right on top of your game and able to nail them five times out of six, it's a pointless ball to try."

Perhaps greater specialisation of bowlers will help - with T20 specialists able to hone their yorkers meticulously, like their predecessors in first-class cricket once perfected bowling at a nagging length just outside off stump. Jones believes that yorkers simply aren't practised enough. "This is why some bowlers are now becoming specialists because they need to practise yorkers, which is a different motor pattern."

With every passing year, the evolution of modern batting makes attempting a yorker more hazardous. The traditional notion that, for fast bowlers, the batsman is a stationary target is being shattered. Perfect yorkers to batsmen adhering to an orthodox stance are turned into full tosses by batsmen gallivanting down the wicket with impunity. Batsmen, too, have honed approaches specifically designed not merely to survive yorkers but smash them: lower backlifts, like those of MS Dhoni or Jos Buttler, are ideally tailored to hitting yorkers and any deliveries that fractionally miss the spot; players also practise how to get contact on yorkers that land just within the tramlines outside off stump. Batsmen like Dhoni are also adroit at knowing when to leave such wide yorkers, so they are called wide. And, especially in the death overs, batsmen set themselves for yorkers, looking to exploit any slight error in length.

Bowlers attempting a yorker in the death overs know how effective the delivery can be - which is why, in the last two years of the IPL, yorkers have been more common than ever before, at a little over five per completed match. But bowlers also know the tightrope they are walking when attempting a yorker - and the very knowledge of these stakes creates even greater pressure.

There never was a golden age for yorkers in T20. For most who try it, the idea of the yorker has always been rather better than the reality.

With stats inputs from Gaurav Sundararaman