YOU SAID:

He never knew what hit him until it ball smacked him.

INTO JAPANESE

ボールが彼を叩くまで、彼は何が彼を襲ったのかを知りませんでした。

BACK INTO ENGLISH

He didn't know what hit him until the ball hit him.

INTO JAPANESE

ボールが彼に当たるまで、彼は何が彼に当たったのか知りませんでした。

BACK INTO ENGLISH

He didn't know what hit him until the ball hit him.