I strongly recommend Evan Lazar's "After Further Review" article, especially this explanation of how the Patriots' run defense is being built. I now think that I understand why Spillane is so important to the Patriots' defense:
Breaking down the tape from Sunday's home win over the Browns, where the Patriots offense and QB Drake Maye aced their toughest exam yet.
www.patriots.com
"On paper, it didn't seem likely that the Browns would beat the Patriots in the passing game. Instead, the path for Cleveland was a great defensive performance supplemented by a strong rushing attack, which is what they got in the Browns 31-6 win over Miami in Week 7.
On Sunday, the Patriots became the first defense to go eight games without allowing a 50-plus yard rusher since 1950, holding Browns rookie RB Quinshon Judkins to 19 yards on nine attempts. As a team, Cleveland only had a 29% success rate on the ground (22nd percentile), with a 31-yard jet sweep propping up their averages. Heading into Week 8, Judkins ranked third in the NFL in rushing yards after contact (420) and had produced 21 forced missed tackles (tied for eighth among RBs). By taking out the run game, rookie QB Dillon Gabriel was forced to drop back 37 times, which wasn't a winning formula for Cleveland.
Schematically, the fun part is how the Patriots are fitting the run in their new system under head coach Mike Vrabel. New England used to run a two-gapping system that prioritized setting or "boxing" the edges, meaning the edge defenders funneled the ball back inside to the run-stuffers. The old mantra was "no edge, no chance."
Under Vrabel, the Patriots have different front mechanics, where they want to "spill" the ball to the outside rather than force it back inside. New England often uses "lever-spill-lever" run fits. In these schemes, the edges actually crash down inside, as does the play-side linebacker to "splatter" the second puller, while the safety is the "force" who sets the edge of the defense, allowing the MIKE to fly free to the ball carrier."