$A$ player catching a moving ball moves his hand backwards. Why?

(N/A) According to Newton's second law of motion,the force exerted by the ball is given by $F = m \times a$,where $a = \frac{v - u}{t}$.
By moving his hands backwards,the player increases the time $(t)$ taken to bring the ball to rest.
Since force is inversely proportional to time $(F \propto \frac{1}{t})$,increasing the time reduces the impulsive force exerted by the ball on the player's hands.
This prevents injury and makes it easier to catch the ball.