Contrast and Wobble

The two kinds of swing so far both make demands. Conventional swing needs the bowler to angle the seam and keep it there. Reverse swing needs real pace, or a badly worn ball, or both. Between them sits a quieter third kind that asks for almost nothing — and it is why you'll sometimes see a gentle medium-pacer suddenly moving an old ball through the air as if he'd learned a secret. In a sense he has. It's called contrast swing, and it comes from the two sides of the ball alone.

Swing with the seam pointing nowhere#

Every swing we've met so far uses the seam as a pointer — angled at the slips, or at leg, or deliberately worked against. Contrast swing throws that away. Here the bowler holds the seam bolt upright, aimed straight down the pitch at the batter, not angled at all. The asymmetry that bends the ball doesn't come from the seam's angle. It comes purely from the difference between a polished side and a rough one.

The clever twist is that the direction of contrast swing is set not by the seam but by speed. At ordinary pace, the smooth side stays laminar and lets go early, while the rough side trips turbulent and clings late — so the ball swings toward the rough side. Push the pace up, and both sides go turbulent, but the rough side's flow is thicker and weaker and gives up first — so the ball swings the other way, toward the smooth side. Same ball, same seam-up grip; the speed alone decides which way it goes. It was Mehta who named and pinned this down, after watching academy bowlers “reverse” a ball that was really doing this instead; later wind-tunnel work measured the seam-straight side force and confirmed it.

Why this one is for everyone#

Here is what makes contrast swing quietly important. Conventional and reverse both need a prominent, intact seam to do their work — the ridge has to be there to trip the air or to weaken it. Contrast swing doesn't. It will work with a bashed-in, flattened seam, because the seam isn't the tool — the two surfaces are.

And a seam pointed straight down the pitch is the easy release. It's how most medium-fast “seam bowlers” already deliver the ball. So you can hand contrast swing to a bowler who could never hold a twenty-degree seam angle at pace, and as long as he has one shiny side and one rough one, he'll swing it without changing a thing about his action. It democratises movement: no express pace, no delicate seam-craft, no guarded grip. One maintained side of the ball, and the physics does the rest.

The wobble ball#

There's a modern cousin worth naming in the same breath, because it also lives in the seam-straight family and because you'll hear about it constantly with today's bowlers: Anderson, Bhuvneshwar Kumar, Mohammed Shami. It's the wobble-seam ball — and strictly it's a movement-off-the-pitch trick more than an in-the-air one, but it belongs here.

Instead of spinning the ball cleanly so the seam holds a steady angle, the bowler releases it with the seam deliberately wobbling, scrambled, not locked by backspin. The result is that neither the bowler nor the batter can be sure which way the seam will be pointing when the ball lands — so it can nip either direction off the pitch, unpredictably. It became a signature weapon precisely for the conditions where conventional swing dies early: with the harder, flatter-seamed balls used in much of the world, a bowler who can't rely on the ball swinging for long can still trouble batters with a seam he himself can't fully predict.

Reading it on television#

Put the three kinds together and you have a simple rule for watching swing that works from your sofa. Look at where the seam points versus where the ball goes.

• Seam points where the ball swings: conventional swing.
• Seam points the opposite way to the swing: reverse swing.
• Seam pointing straight down the pitch, and the ball still curves: contrast swing.

One glance at the seam, and you know which of the three you're watching — and therefore what the bowler is actually doing.

All of which assumes the bowler has a ball that behaves. But not all cricket balls do the same things, or for the same length of time. Three different factories make the balls used in Test cricket, and each one turns the sport into a subtly different game. That's next.