A cricket ball is made of cork with stitches encircling it from the centre. The stitches are called the seam. Unlike a tennis ball that has rubber content for better bounce, the cork’s stiffness does not allow it bounce as easily on the cricket pitch. This becomes even more trickier as the pitch is a culmination of grass, sand, and soil.
The cricket pitch is 22 yards long. Bowlers have to hurl the cork ball in a way that is bounces off the pitch once to reach the batter. Predominantly, the two types of bowlers in cricket are pacers and spinners. While spinners use their fingers and wrist to inculcate variations on the ball, seamers use the seam of the ball along with pace to create variations.
Seam bowling is an art of pace bowling where the bowler aims to pitch the ball such that the seam strikes the pitch. The threaded seam is slightly raised. Hence, upon bouncing, the seam creates a deviation as it reaches the batter. The pace of the ball can be fast, medium, or slow. The bowler’s focus primarily is to release the ball in a manner that the seem strikes the pitch.
In addition to the seam, bowlers tend to shine one half of the ball. This leads to the ball drifting mid-air due to changes in resistance of the air on the shiny and dull sides. The resulting variation is one where the ball swings at a quick pace.
A seam bowler usually positions his or her middle and index finger on the seam while gripping the ball with the rest of the fingers and the palm. This keep the seam in a vertical position, thereby increasing its chances of striking the pitch. A cross seam delivery is one where the seam is horizontal to the index and middle fingers. Cross seamed deliveries can be slightly slower but can create an effective variation if bowled properly.
Seam bowlers also use variations like off cutter and leg cutter. However, these techniques require the bowler to roll their fingers off the ball which significantly reduces the ball’s pace, and also reduces the chances of the seam hitting the pitch or the deck.
It is said that compared to cricket from the 20th century and the early 21st century, ball manufacturers have substantially reduced the level of seam. This has made the ball relatively flatter and even, thus decreasing the amount of variation. Glenn McGrath, Wasim Akram, Waqar Younis, Curtly Ambrose are some prominent seam bowlers from the late 1990s to early 2000s. Modern seam bowling greats include James Anderson, Mitchell Starc, Mitchell Johnson, Mohammad Shami, and Trent Boult.
