The arm ball is more dangerous than the one that turns

Batters play the spinning delivery because they can see it happen; the one that goes straight on gets them lbw.

Check the dismissal columns of any decent finger spinner over a season and count how many wickets came from the ball that turned. Fewer than you would guess. Bowled through the gate and caught at slip get the replays, but a large share of the honest work is lbw and bowled by the delivery that did not deviate at all, and that is not an accident of luck. It is the design.

The mechanism is about expectation. A batter facing an off-spinner sets himself for the ball coming in to a right-hander, so his front pad goes across, his bat comes down inside the line and he plays for turn that has not been earned yet. Send one down with the same arm speed and a seam angled towards slip so it holds its line, and every part of that preparation is now wrong. The pad is where the ball is going. He has played around a straight one, which is the least dignified way to be dismissed and the most common.

What makes it work is not the delivery itself but the ratio. Bowl arm balls too often and the batter stops committing, and then your stock ball loses its threat too, because the whole system depends on him believing the ball will turn. One in eight, maybe one in ten, and never twice in an over. The most underrated skill in spin bowling is restraint.

Modern coaching does not help. Everything rewards the visible product, the ball that rips, because it looks like effort on a video and gets shown to a selector. Nobody clips together a montage of deliveries that went straight.

There is a legitimate objection. Against left-handers and on surfaces with real turn, the straight one is far less useful, and a bowler who relies on it will be swept from outside off all afternoon.

Fair enough. But most first-class pitches on most days do not turn much, whatever the pre-match talk promised, and on those days the bowler who can hold his line and wait for a pad is the one who ends up getting paid.