美國職業棒球大聯盟的規則手冊並未包含對揮棒動作的官方定義，但將揮棒定義為“嘗試
擊球”。由裁判決定是否出棒。通常，在裁定中考慮諸如球棒通過本壘板板的前面還是擊
球手向後拉手腕等因素。一些裁判更喜歡使用“翻轉手腕”標準來確定選中的揮棒動作：
如果手腕“翻轉”，則會發生揮棒動作。
原文：The Major League Baseball rulebook does not contain an official definiti
on for a checked swing, but defines a swing as "an attempt to strike at the ba
ll". It is the decision of the umpire as to whether an attempt was made or not
. Generally, factors such as whether the bat passes the front of the plate or
the batter pulls their wrists back are considered in the ruling. Some umpires
prefer to use the "breaking the wrists" criterion as the method to decide a ch
ecked swing: if the wrists "rolled over", a swing occurred.
所以就真的沒有明說怎麼麼樣叫出棒過半啊，連大聯盟都沒寫了。只有寫裁判習慣怎麼判
，沒有寫怎麼判是對的，蔡明里是在哈囉？
不過影片還真的很難判斷是否有出棒。