#NewsBytesExplainer: The dynamics of seam bowling
What's the story
"Make the new ball count!"
The phrase is often used moments before a seamer reaches his run-up.
Seam bowling is the primitive form of fast bowling, which every seamer learns at the grass-root level.
The decks which don't bring much swing into play usually give bowlers a room to unfold seam movement.
Let us understand the dynamics of seam bowling.
Derivation
What is seam bowling?
Seam bowling is a technique used by fast bowlers wherein the ball is pitched on to the seam in order to cause deviation.
The ball changes trajectory after pitching on the surface.
Generating seam movement does not mean the bowlers necessarily will have to notch over 90 KPH.
Bowling at a decent speed could also perturb the batsmen with movement.
Physics
How does the ball move after pitching?
A conventional cricket ball comes up with circular stitching to join its two halves.
The stitching is known as seam which is slightly raised above the surface.
Hence, when the ball pitches on the seam, it causes irregularity and could deviate on either sides of the wicket.
The ball may travel straight or move sideways, thereby putting the batsmen in doubt.
Difference
Difference between swing and seam bowling
Many people confusing seam bowling with swing.
Swing bowling is an altogether different subtype of fast bowling where the ball moves in the air before pitching.
The ball could either swing into the batsman or move away.
In seam bowling, the majority of work is done after the ball gets pitched.
However, both forms depend firmly on the grip of the ball.
Grip
The seam is held upright in order to achieve movement
For making the ball seam, a bowler must grip the ball perfectly.
The ball is held with the wrist behind it and seam held upright.
Keeping the seam vertical, the ball is held from the first two fingers and thumb.
Meanwhile, the other two fingers lean downwards, supporting the ball.
Glenn McGrath's grip is often deemed as the best in world cricket.
Variations
Seam bowling involves two different variations
There are two types of variations in seam bowling - leg cutter and off cutter.
A lug cutter is bowled by placing the middle finger on the seam with the index finger about two centimetres away.
The ball cuts into the right hander here.
While bowling an off cutter, the entire process is reversed.
In this case, the ball veers away from the right-hander.
Wicket
Seam movement on different tracks
Decks play a pivotal role in generating seam movement.
The bowlers are able to produce more movement on a hard strip that is studded with cracks.
Cracks give rise to deviation as the varied surface constitutes movement.
On such tracks, the ball changes its path after it hits the crack.
Green-tops also enhance this effect, owing to the extra grass cover.
Bowlers
Glenn McGrath's line and length complement the seam movement well
Australia's Glenn McGrath is the greatest ever exponent of seam bowling.
Although he used to bowl at an average pace, his impeccable line and length was nightmare for batsmen.
McGrath would often jeopardize legend Sachin Tendulkar with such relentless seam movement.
Courtney Walsh and Curtly Ambrose were absolutely terrifying with the moving ball.
Ishant Sharma also used this art profusely during his early days.