If you are the catcher and either do not catch or drop the third strike, the batter becomes a base runner and can advance to first base. To complete the out, you must then pitch the ball to first. Otherwise, the batter is safe for now. This is why it is important for catchers to field their position well. There are two reasons why your team's catcher might want to throw to first instead of tagging out: 1 If the catcher does not catch or tag out the baserunner, then he has allowed his pitcher to be hit by a thrown rock or beanball. 2 It gives the catcher a chance to get the next hitter out if the first pitcher hits someone or allows someone to reach base. In conclusion, because throwing to first allows your team to make more outs and avoid giving away runs.