A fielding side that begins with four slips often has none by the middle of a session. The reduction follows directly from how the probability of a catch changes.
Why a slip exists at all
Slip fielders stand behind the batter on the off side to intercept edges that fly off the face of the bat. They are positioned where the ball travels fastest and where a batter has least control.
The position is only worth staffing when edges are likely and when they carry through the air. Both conditions are met by a hard, new ball bowled at pace.
Every slip is a fielder removed from run prevention elsewhere. A cordon is therefore a deliberate trade of containment for the chance of a wicket.
Edge frequency falls as the ball ages
Movement through the air and off the seam produces edges by beating the bat marginally. As the ball loses shine and the seam flattens, that movement diminishes.
Batters also adjust once they have faced enough deliveries to judge pace and bounce. Established batters edge the ball less often than those who have just arrived.
The combination means the rate of chances drops sharply within the first hour or two. The cordon becomes idle rather than merely unlucky.
Carry is the second variable
An edge must reach the fielder at catchable height. A hard ball retains energy after contact and travels further, while a softer ball drops shorter.
Slips therefore move closer as the ball ages, and eventually the distance required becomes impractical. A catch that would land in front of a fielder is not a chance.
Surfaces with low bounce compress this timeline further. On such pitches captains may never post more than two slips at all.
What the fielders are redeployed to do
Removed slips typically go to catching positions squarer of the wicket or into run-saving positions in the ring. The choice signals whether a captain is still attacking.
Against a set batter, the priority usually becomes restricting scoring to force an error. Fielders in the ring cut off singles and increase pressure over time.
Spinners require an entirely different arrangement, with close catchers on the leg side and protection on the boundary. The cordon does not simply shrink, it is replaced.
When the cordon returns
A new ball taken after the permitted number of overs restores hardness, shine and seam. Captains rebuild the slips immediately, often for a short and intense burst.
Reverse swing can also justify a return, since it produces late movement and edges even with an old ball. The cordon in that case is usually narrower and finer.
The pattern across an innings is therefore cyclical rather than linear. Field settings track the physical state of the ball more closely than the scoreboard.
