Heard About Reverse Swing ...How About Contrast Swing ?

Just as the mysteries of reverse swing have begun to unravel, a NASA scientist — a schoolmate of Imran Khan — has come up with a new theory of what he calls `contrast' swing.

Dr. Rabindra Mehta, who is also a sports aerodynamics consultant, says that England's fast bowlers in India have made the ball swing towards the smooth side after learning the new technique from former England and now Australia bowling coach Troy Cooley.Troy Cooley has been working on this with the England bowlers over the winter. It was noticeable in Nagpur that Matthew Hoggard, not known as a reverse swinger, managed to get the old ball to swing.
This was contrast swing.

"Whenever an old ball swings, commentators label it reverse swing. Often though, it is not true reverse swing they are observing, but what I call `contrast' swing," writes Dr. Mehta, who has spent 25 years studying how a cricket ball swings, in the April issue of The Wisden Cricketer

"For conventional swing (away), the ball is released with the seam angled towards first slip or fine leg, spinning backwards along the seam and with the polished, smooth side facing the batsman. The ball will then swing in the same direction as the seam is pointing.

"For true reverse swing the ball is released in the exact same way, except with the rough side facing the batsman. In this case, the ball will swing in the opposite direction to that of the seam. But, if a sharp contrast in surface roughness is generated on the ball, so that one side is smooth and the other rough, the ball can be made to `contrast' swing with the seam positioned vertically (pointing straight down the pitch)."

Here’s a quick guide to the difference between contrast and reverse swing:

1) Contrast swing relies on an upright seam rather than the angled seam pointing away of reverse swing.
2) Contrast swing will work even when the seam is bashed in, and doesn’t rely on a prominent seam unlike conventional and reverse swing.
3) It’s called contrast because of the contrast between the two sides of the ball : one very rough and the other smooth.
4) In contrast swing the ball swings towards the rough side at less than 70mph and towards the smooth side at higher speeds. This one goes both ways.
5) If the seam is pointing down the pitch then it’s contrast swing.

Dr. Mehta says in the article that it’s easier to produce than reverse swing because it doesn’t require the bowling speeds and prominent seam unlike reverse swing. However, moving away from the article, it’s said that not all bowlers who have attemped to do it have been able to master the skill. Not mentioned in the article, but other things to look out for in contrast swing is that the movement comes very late and is unlikely to happen unless the ball is 40 overs old.