Seam bowling is again a rather confusing category in isolation, as any fast bowler will make use of the seam on the ball in some way. However, defined strictly, a seam bowler is anyone that bowls the ball directly onto its seam to cause deviation off the pitch.
The logic for this is easily understood. A cricket ball is not a perfect sphere - the stitching on the seam (which joins the pieces of leather) is raised and the irregularity means that a bowler can create sideways movement if it bounces on the pitch. The stock delivery for the seam bowler is therefore one with the seam upright and the ball moving around its horizontal axis to ensure the seam faces the batsman vertically at all times.
The minor deviation which can result is often the difference between a nick from the batsman and a regulation defensive stroke. Australia’s Glenn McGrath, in particular, was a master at this art and, generally speaking, seam bowling is the preserve of medium fast or fast medium bowlers. The importance of retaining good line and length means that speed is usually of secondary importance; otherwise the movement could only make an easy attacking shot even easier.
There are also variations on the stock ball. By holding the seam in different ways, it is possible to experiment with the movement off the pitch:
- Off cutter - Achieved by keeping the first finger on top of the seam with the thumb directly underneath (also gripping the seam) and the middle finger down the right hand side of the ball (if right-handed). By changing the grip, the spin placed on the ball is altered and so too is the movement off the pitch. When facing a right-handed batsman, the movement will be from the off-side to the leg-side (hence the name off cutter, as it cuts away from the off-side). Former greats like England’s Fred Trueman and Waqar Younis were particularly effective with the off cutter.
- Leg cutter - Moving from the leg-side to the off-side in contrast to the off cutter, the technique for achieving a leg cutter is naturally the opposite to the off cutter. If you are a right-handed bowler, grip the seam with the first finger and the thumb and place the middle finger down the left hand side of the ball. The small movement away from the batsman will increase the chances of a nick on the ball, making it an excellent wicket-taking delivery for the seam bowler.