Shoulder alignment tells you more about a spinner than revolutions

Revolution counts have become the fashionable number in spin bowling, and they explain less than where the front shoulder points.

The revolution count is a lovely number. It is measurable, it sounds scientific, and it fits neatly into a graphic. It also tells you comparatively little about whether a spinner will trouble a good player.

Two bowlers can impart the same rotation and produce completely different problems, because what the ball does after pitching depends on the axis it is spinning around and on the angle it arrives at, and both of those are set upstream at the shoulder. A front-on spinner with a high revolution count often gets over-spin, which produces bounce and dip but a fairly predictable line. A side-on action with the same energy tips the axis over and turns the same revolutions into deviation off the surface. Same input. Different question for the batter.

This is why I distrust the coaching instinct to chase revs. Once a young bowler is told the number is the target, he will find it, usually by muscling the delivery with the wrist and losing the shoulder rotation that gave him the release angle in the first place. His numbers improve and his bowling gets easier to face. I have watched that trade made more than once and it is never announced as a trade.

The seam bowling literature made this mistake earlier and has largely recovered from it. For a while everything was about wrist position at release, and then the biomechanists pointed out that shoulder and hip separation upstream determines how much the wrist can even do. Counter-rotation of the trunk, the gap between where the hips are pointing and where the shoulders are pointing at front foot contact, is the thing that generates both pace and lateral movement, and it is also the thing most closely tied to lower back stress injuries in young quicks.

That last point is the reason to care beyond aesthetics. A metric that is easy to collect will get collected, and then it will get coached, and then people will change their bodies to satisfy it. If the metric sits downstream of the mechanism, you have just paid an injury cost for nothing.

Film the shoulder. Watch it in slow motion from square. The stopwatch and the rev counter can wait, because they are describing the result of a decision the bowler made half a second earlier and about a metre further back.