an umpire isn't readily able to examine and remove a ball from play after a 4-3 (or any groundout) is completed . . . whereas he is readily able to examine the ball and remove it from play after a strikeout if he deems it is too scuffed, etc. the physical reaction of the ball hitting the bat and then the field may create "imperfections" in the ball that are favourable to the pitcher and defense--and not to the offense.