Someone who has been out there in the spotlight as often as he has cannot remain wholly unknown.

【翻译】像他那样经常出现在聚光灯下的人，不可能是个完全默默无闻的人。

【分析】Someone （主语）who has been out there in the spotlight as often as he has （定语从句，本身是一个比较结构） cannot remain wholly unknown.（谓语部分：是个系表结构）

out there：直接理解为“在那里”，指某一地方，out 和there 都是地点、方位副词，其实，be in the spotlight （在聚光灯下）才是句子的主要成分。