The sharp downward deflection, due to gravitational pull, in the tail end of the yorker's trajectory causes difficulty in judging the length, whereas a flat delivery that lands near a batsman's feet can be judged and played without much difficulty.
The sharp downward deflection, due to gravitational pull, in the tail end of the yorker's trajectory cause batsmen difficult to judge the length. Whereas a flat delivery that lands near batsman's feet can be judged and played without much difficulty.