NFL Connections #37, Answers
The full solution: all four groups and the 16 names, sorted from the easiest group to the trickiest.
Played at Nebraska
Ndamukong Suh, Ahman Green, Grant Wistrom, Mike Rozier
Played at Wisconsin
J.J. Watt, Russell Wilson, Melvin Gordon, Joe Thomas
Played at Iowa
Dallas Clark, Bob Sanders, George Kittle, Marshal Yanda
Played at Michigan State
Le'Veon Bell, Kirk Cousins, Tony Mandarich, Bubba Smith