The former base-ball player, who used to be called "the star of the middle-aged generation," passed away.
He was a great player, even when he was in his middle age.
ご質問ありがとうございます。
"The former base-ball player,"＝「元野球選手」
"who used to be called "the star of the middle-aged generation,"=「『中年の星』と呼ばれていた人が」
"passed away."＝「亡くなった。」
"He was a great player,"＝「彼は素晴らしい選手だった」
"even when he was in his middle age."＝「中年の時でも。」
ご参考までに。
アメリカ合衆国 
