The pitcher was shorter than he was. All the pitchers were. His bad luck again, he was the biggest kid in the league. It was a weird kind of leverage for them; if they sank the ball enough, it would come in at the low edge of his strike zone.
Интересует выделенная часть, остальное контекст.
В бейсболе есть вид подачи sinker – с нырком мяча.