Fyi,the Jags run defense was 7th best in yards per attempt after the Marcell Dareus trade over the last 9 weeks. Not saying it is amazing but I would not call it bad anymore.
It was terrible the first 7 weeks which skews numbers....
For additional info, they were dead last at 5.16 pre Dareus. Post 3.69.
Yards per carry is a flawed metric (every metric is, really), but let's ignore that. Was it Dareus? Or was it the schedule? The correct answer is probably a little bit of both. These are the teams they played over those last 9 weeks, and their ranking in rushing yards per carry:
Bengals - 29th
Chargers - 26th
Browns - 6th
Cardinals - 31st
Colts - 28th
Seahawks - 21st
Texans - 16th
49ers - 17th
Titans - 15th
One team in the top third of the league (though it's the Browns, which.... c'mon). Three teams in the top half of the league (though the two non-Browns teams are the two lowest ranked teams in the top half). Five teams in the bottom third of the league, including 4 of the worst 7 teams in the league.
Contrast that to their first 7 games:
Texans - 16th
Titans - 15th
Ravens - 19th
Jets - 20th
Steelers - 25th
Rams - 7th
Colts - 28th
One team in the top third of the league. Three teams in the top half of the league (though again, with two as low as you can get and still be in the top half). Two teams in the bottom third of the league.
Jacksonville sure played a lot of shitty rushing offenses, huh? And yet, they still finished with bad rushing defense stats. Seems like a salient point.
While we're at it, let's look at the passing offenses they've faced, and their rank in net yards/attempt:
Texans - 20th
Titans - 17th
Ravens - 32nd
Jets - 21st
Steelers - 6th
Rams - 7th
Colts - 29th
Bengals - 22nd
Chargers - 2nd
Browns - 31st
Cardinals - 23rd
Colts - 29th
Seahawks - 15th
Texans - 20th
49ers - 18th
Titans - 17th
Three top-10 passing offenses, four middling passing offenses, and a bunch of teams in the bottom third of the league. So they played a lot of shitty passing offenses too. (Which is a point I've made a few times throughout this season: Jacksonville has beat up on a bunch of bad offenses. Hey, you can only play the team in front of you. But let's see this defense do it on the road in Foxboro.)
Bringing it back to the running game: the Patriots will be the best rushing team they've faced outside of the LA Rams. Those Rams finished 7th in yards per attempt, 8th in rushing yards, and 9th in rushing DVOA. Pats finished 12th in rushing yards per attempt, 10th in rushing yards, and 3rd in rushing DVOA. Gurley finished with 116 yards on 23 carries, in case you were wondering.
The Steelers made the mistake of coming out empty set, trying to spread the Jags out and throw the ball against the best passing defense in the NFL. I don't think the Patriots will make the same mistake. I don't think they'll be afraid to throw it (take another look at that schedule the Jags played). But I don't think Brady will be throwing the ball 50+ times again unless something went horribly wrong and they have to play catch-up. The running game should be a big part of the offensive plan.