There is no way a 13 yr old is capable of discerning what a batters weakness should be , especially not while she is pitching to her. But a good coach can see what a batter is doing wrong, and call pitches that take advantage of that. He will also record /remember what worked, what didnt, what this batter did during previous at-bats, and draw on that every time a batter comes up in a game, or a tournament, or a season, or even several years of facing the same players.