The Jaguars are 2-2, tied for first in the AFC South and have outscored opponents 109 to 74. A big part of their early season success is due to the defense, which ranks seventh in the league, according to Football Outsiders' metrics.

The Jags held the Texans to 203 yards in the season opener and the Ravens only managed 186 yards two weeks later -- both Jacksonville wins. But in Week 2 the Titans were good for 390 yards, including 179 yards on the ground, and the Jets bettered those numbers on Sunday: 471 total yards and 256 rushing yards. And therein lies the problem: For as good as Jacksonville has been in defending the pass, they've been just embarrassingly incapable of stopping the run.

The differences are as stark as they are incomprehensible; Football Outsiders rates the Jags as having the league's best pass defense ... and its worst rush defense. 

  • Week 1 vs. Texans: Lamar Miller -- 17 carries, 65 yards, 0 TDs (longest run: 8 yards);
  • Week 2 vs. Titans: Derrick Henry -- 14 carries, 92 yards, 1 TD (longest run: 17 yards);
  • Week 3 vs. Ravens: Alex Collins -- 9 rushes, 82 yards, 0 TDs (longest run: 19 yards);
  • Week 4 vs. Jets: Bilal Powell -- 21 carries, 163 yards, 1 TD (longest run: 75 yards), Elijah McGuire -- 10 carries, 93 yards, 1 TD (longest run: 69 yards)

This week, the Jaguars travel to Pittsburgh to face the Steelers, who have one of the league's most balanced offenses; the unit ranks seventh overall, seventh in passing and seventh in rushing. Oh, and the NFL's most dynamic player a season ago, running back Le'Veon Bell, appeared to find his form last week in Baltimore after a slow start following a training camp holdout. He shredded Baltimore for 144 yards on the ground that included two scores, and added another 42 receiving yards.

"We know it's bad," nose tackle Abry Jones said this week, via Jacksonville.com, of the unit's Jekyll and Hyde season to date. "The defensive line is really paying attention to it. As a defensive line, we take it personally."

Coach Doug Marrone cautioned that it's not all on the front four.

"It's easy to point the finger at the first level," Marrone said. "But then you get to the second level: Who's going to cover out butt? And then you have the third level, the final level, of who's going to cover it?"

Bell, meanwhile, is the NFL's most patient runner, willing to stop behind the line of scrimmage until a hole opens. This makes an already difficult job even more so for the Jaguars.

"Our one-gap scheme is going to have to hold true," safety Barry Church said. "We can't have people going from this gap to try to make the play in that gap because he's super patient to where he will wait for that to happen and then, boom, he is out of the gate. We've practiced long and hard for this."

CBSSports.com's eight experts remain unconvinced; they're all picking the Steelers to win, and seven of them expect the Steelers to cover the spread.