Wednesday, October 08, 2008

Three ways to bowl a doosra

There are three main ways to bowl a doosra: 1. a back-chuck/ weak throw; 2. with shoulder rotation; 3. with body rotation.

I will define a true doosra as a leg-break delivered with the back of the hand facing the batter, and the forearm in anatomical supination.

(Supination means the forearm is rotated in the opposite direction to the leg-spinner. Leg spinners have the forearm pronated. If the arm is held out in front with the thumb upright, moving the thumb outwards (clockwise) is supination, moving the thumb inwards (anticlockwise) is pronation.)

The big problem with the doosra is imparting sufficiently rapid rotations onto the ball. This is the reason why most off-break bowlers do not bowl the doosra - it is not that they can't spin the ball at all, but that without some extra way of applying spin the ball is merely gently-rolled from the fingers, and the rotations are so slow that the ball is barely spinning.

1. Back-chuck

The back-chuck/ weak throw is the method used by most of the doosra bowlers whose actions have been reported or declared illegal. This involves rolling the ball towards slips with the fingers and wrist, but using the snap of an elbow-straightening/ throwing action to add extra rotations and pace onto the ball. This kind of doosra is a useful delivery since the spin and pace are potentially both enhanced by throwing. As I said, this is currently usually regarded as an illegal delivery (if the arm straightens more than 15 degrees). However, I think the back chuck should if possible be legalized.

2. Shoulder rotation

Shoulder rotation is used by Muralitheran, and is probably only possible for someone with a permanently bent elbow. Murali's stock off-break is delivered by twisting the whole arm from the shoulder so the bent elbow moves from right to left, plus swivelling the wrist, to deliver the ball from the back of the hand over the gap between the thumb and index finger.

For the off-break Muralis fingers seem to pass over the top of the ball from right to left and releasing the ball towards leg slip (for a right handed batter). It has been described as similar to someone unscrewing a lightbulb clockwise and very fast.

Murali's doosra seems to be delivered by bending the wrist back on itself during delivery so that the fingers pass _under_ the ball from left to right and releasing the ball towards slips (for a right handed batter).

3. Body rotation

The other method for bowling a doosra seems to be that employed by Saqulain Mushtaq, who is credited with inventing the delivery: body rotation.

This gets a bit more rapid revolution of the ball because it is more of a top-spinner than a doosra, and the wrist has a larger range of movement in that side-on top-spin position. But the ball moves towards the slips (for a right handed batter) because Saqlain's arm swings across his body from right to left, and his body is swivelled round so that it is as if he is bowling at 45 degrees to the left of the batter, looking over his right shoulder.

Imagine coming-up to bowl at a right hander, but at the last moment swivelling around an extra 45 degrees anticlockwise and bowling at slip. This swivel brings the arm into such a position that a top spun delivery turns into a leg break. Then you would need to aim the ball at the stumps from this position, to replicate Saqlain.

I think that Johan Botha is trying to do the same - at the point of delivery he has rotated so far that he has almost turned his back on the batsman.

The body rotation method actually builds the bowling action around the doosra as the stock delivery (or at least a frequent one), and the off-break becomes a variation.

The problems with bowling the doosra using body rotation is that 1. the doosra is still rather a slow spinining delivery, slower than the conventional off break or leg break; and 2. the off break variation is sub-optimal, since the necessary degree of body rotation is less effective at generating spin than the usual off break bowlers action.

In conclusion, unless the back-chuck is legalized, then Murali will probably be the only bowler ever to posess a really fast-spinning doosra.