NFL Connections #56, Answers
The full solution: all four groups and the 16 names, sorted from the easiest group to the trickiest.
Mobile QBs of today
Lamar Jackson, Josh Allen, Kyler Murray, Jalen Hurts
Pioneering dual-threat QBs
Randall Cunningham, Michael Vick, Steve Young, Fran Tarkenton
Pass-catching running backs
Marshall Faulk, Christian McCaffrey, Roger Craig, Alvin Kamara
Scrambling QBs of the 2000s
Donovan McNabb, Daunte Culpepper, Steve McNair, Vince Young