“drop the ball”不是指“把球掉了”，其真正的含义是尤指由于愚蠢或粗心）犯错误；失职

【例句】
You can't trust John to do the job right. He's always dropping the ball.
你不能信任John可以把工作做好，他总是犯错误。

Every time I've ever asked you to do something, you drop the ball.
每次我要求你做的事情，你总是失误。