In what way? Nix is more valuable to his team's success without a doubt. Kent St. was a top 10 defense his freshman season because he was that dominant of a player. They're not a top 20 defense 2 of the last 3 years without Roosevelt Nix.
Aaron Donald has a tremendous impact for his team defensively, although Nix's impact for his team is simply more significant. Kent St. can't recruit like Pittsburgh.
Khalil Mack is the only other defender in the MAC who has that type of impact for his team.