Swing and seam

Swing is sideways movement through the air before the ball pitches; seam is sideways movement off the pitch when the ball lands on its stitching. Both are the fast bowler's tools for beating the bat.

Conventional swing comes from a new ball with one side kept shiny and the other allowed to rough up; the ball curves towards the rough side, so an outswinger leaves the right-hander and an inswinger comes in. It is strongest when the ball is new and the air is heavy, which is why overcast mornings are a fast bowler's favourite weather. Reverse swing is the older ball's version: once the rough side is very rough, the ball begins to swing the other way, late and at pace. Seam movement depends on the pitch rather than the air: on a grassy or damp surface, a ball landing on the seam can deviate either way, and the batter has no way of knowing which.

For a manager this decides selection and the toss. Cloud and a green top mean an extra seamer and a bowl-first call; heat and a flat surface mean the swing will be gone by the tenth over and the plan must be built on something else.

In Masterstroke: swing, seam and the age of the ball are all in play on the live field, and a plan for the powerplay should assume the ball will move.