Looking at these two sites:
https://www.teamrankings.com/nfl/stat/2nd-half-points-per-game
https://www.teamrankings.com/nfl/stat/opponent-2nd-half-points-per-game
Doing some quick math, looks like Seattle (5.9) and Arizona (4.5) have the largest average 2nd half point differential. Didn't see...