トッププレイヤーでしたが年齢を重ねて能力が衰えてきたもののまだまだ大丈夫ということです。
Even though he's past his prime/over the hill, he don't need to retire and is such an amazing baseball player. としてみました。
Even though he is past his prime, he can still be an active baseball player.
Even though he is he is past his prime, he can still continue actively playing baseball.
質問をありがとうございました。
君が言った通りです。
"past his prime" = 全盛期を過ぎた
"to continue actively playing baseball" "to continue to be active in baseball" = バリバリ野球を続けれる
例:
"The actress is past her prime. She won't appear in any more movies now."
その女優は全盛期を過ぎている。もう映画には出ないだろう。
"That band used to be really popular. They are past their prime now."
あのバンドは昔は本当に人気があった。彼らは今全盛期を過ぎている。
prime:全盛期
prime time: 全盛期
例:
"It is prime time to buy a house."
家を買う絶好の時期です.
"March is prime time for planting strawberries."
3月はイチゴを植える最盛の季節です。
Even though he may not be the youngest any more, he can still continue his career as a baseball player.
Even though he may not be the youngest any more, he can still continue being a professional baseball player.
Even though he may not be the youngest any more, he can still be a professional baseball player.
Ikunさん
ご質問どうもありがとうございます。
様々な表現があると思いますが、いくつか自然な表現を紹介します。
- Even though he may not be the youngest any more, he can still continue his career as a baseball player.
- Even though he may not be the youngest any more, he can still continue being a professional baseball player.
- Even though he may not be the youngest any more, he can still be a professional baseball player.
お好みに合わせて使い分けてみてください。
ご参考にしていただければ幸いです。
イギリス 
ドイツ 
