NFL Connections #65, Answers
The full solution: all four groups and the 16 names, sorted from the easiest group to the trickiest.
Played MLB and the NFL
Bo Jackson, Deion Sanders, Brian Jordan, Drew Henson
Undrafted QBs who started
Kurt Warner, Warren Moon, Jeff Garcia, Brian Hoyer
QBs turned broadcasters
Tony Romo, Troy Aikman, Phil Simms, Boomer Esiason
Players turned head coaches
Mike Vrabel, Dan Campbell, Jim Harbaugh, Mike Ditka