The Most Underrated Player in Football Past or Present

I did not expect a stealer to come up, but we'll take it. Who would you say is the most underrated player in football past or present? I thought Troy Polamala was one of the greatest players ever around. What's an interview question that you've found especially insightful when looking at either a potential draft pick or a player to vet? Why do you treasure this player? That to me,. And I'm not answering that because of his stats and how big he is.