Revolutions per minute is the vanity number of finger spin

Spin rate reads beautifully on a broadcast graphic and explains far less about wicket taking than release height and the dip that follows.

The rev counter arrived and immediately became the only thing anyone talks about. Two thousand five hundred revolutions per minute. Two thousand eight. The number sits under a bowler's name like a batting average, and it flatters exactly the wrong bowlers.

Here is what actually troubles a batter. Not sideways deviation off the surface, which he can usually play late anyway, but the ball arriving somewhere other than where his feet have already committed. That comes from dip, and dip comes from the interaction of spin axis, release height and the speed the ball travels through the air. A ball with a genuine over-spin component and a tall release drops out of its arc a metre before the batter expects. He is through the shot. The edge or the miss happens in the air, before the pitch has done anything at all.

You can generate enormous revolutions around an axis that sits close to horizontal and get very little dip for it. Plenty of bowlers do. The graphic still says two thousand six hundred.

Release height is the least glamorous variable in cricket and probably the most useful one for a spinner. It buys steeper bounce, it buys a longer flight path for the drop to work in, and it cannot be coached into someone who does not have it. Which is why tall finger spinners keep succeeding with modest side spin while shorter bowlers with better hands get told to fire it in flatter and eventually become containment options.

I would rather know a bowler's average drop over the last three metres than his rev count, and I suspect the ball tracking firms could give us that tomorrow if a broadcaster asked.

There is a field-setting consequence too. Captains set for deviation because deviation is what they can see. If the wicket taking mechanism is really the vertical error, the catching positions should sit slightly straighter and slightly deeper than most of them do, waiting for the drive that arrives too early rather than the edge that leaves.

None of this means spin rate is useless. It correlates with something real, and a bowler whose revs collapse mid-spell is telling you he is tired. But it became the headline number because it is easy to measure and easy to display, and easy to measure is not the same as important. The ball that gets him is the one that never reaches where he was looking.