on the ball

Miyuki Manabeの「火車」All She Was Worthを読んでいます。
前回は引用文が長かったので今回は短い引用にします。
Honma gave a big nod. "Two more questions.
"
"Okey."
"What did the wife do before they got married?"

"Your regular secretary. Did the odd paperwork, nothing fancy. Plus some accounting, so she must have had something on the ball."
この "on the ball" と云う表現も前に調べた気がしますが、直ぐに意味が頭に浮かばないので辞書を見ます。"
・Oxford English Dictionary: Indicating competence, alertness, or intelligence.: a woman like that, with so much on the ball
・Collins Dictionary: If someone is on the ball, they are very alert and aware of what is happening.: She really is on the ball; she's bought houses at auctions so she knows what she's doing.
この表現の由来を調べました。The Phrase Finderは幾つかの説を紹介していますが、本命説はスポーツのボールゲームから来たとありました。以下はThe Phrase Finderからの抜粋です。
The phrase 'on the ball' did actually originate in the sporting arena, but relates to the eyes rather than the feet. It is a contraction of the earlier expression 'keep your eye on the ball', which advice has been given to participants in virtually every known ball game.