雖然很多人很氣
覺得裁判亂判
但是根據大聯盟的rule book
definition of terms
A FAIR BALL is a batted ball that settles on fair ground between home and first
base, or between home and third base, or that is on or over fair territory when
bounding to the outfield past first or third base, or that
touches first, second or third base, or that first falls on fair territory on or
beyond first base or third base, or that, while on or over fair territory touch
es the person of an umpire or player, or that, while over fair territory, passes
out of the playing field in flight.
太長我直接抓重點
“while on or over fair territory touches the person of an umpire or player”
線本身包含在fair territory裡
當防守球員碰到球的瞬間，球"on"或者是"over" fair territory，就算fair ball
所以即使球本身沒有on在線上，只是over在線的上空也算界內區
Official Baseball Rules
2026 Edition
p.151