Week 15 of the NFL season always brings fascinating schematic battles as teams jockey for playoff positioning. This week was no exception, with several notable trends emerging across the league.

Heavy personnel packages were in vogue this week. Teams used 12 and 13 personnel (2+ tight ends) on 28% of offensive snaps, the highest rate of the season. This reflects the cold weather in many stadiums and a desire to control the clock.

On defense, teams continued the trend toward two-high safety shells. Cover 2 and Cover 4 looks were used on 52% of passing downs, as defensive coordinators tried to take away the deep ball and force offenses to be patient.

In the red zone, we saw a significant uptick in play-action usage. Teams ran play-action on 35% of red zone plays, up from 28% earlier in the season. The Eagles and Cowboys were particularly aggressive with this approach.

Blitz rates dropped to a season-low 24% league-wide. Coordinators seem to be trusting their coverage more as the season progresses, preferring to rush four and drop seven into coverage.

One fascinating development was the increased use of empty backfield sets. Teams used empty formations on 15% of snaps, the highest rate in NFL history. The Dolphins and Bills led the way with this approach.

Finally, we noted a trend toward aggressive fourth-down decision-making. Teams went for it on fourth down 55% of the time when analytics suggested they should, up from 45% at the start of the season.