The perceived weakness of the New England Patriots -- and it can only be perceived on an unbeaten team -- is their aging defense.
Specifically, as many pundits are quick to point out, their linebackers are too old and too slow to hold their own against a power running game.
And that is primarily what has given life to a popular notion that they can bring an end to the Patriots' pursuit of perfection.
Picture the Jaguars' ultra-large, ultra-powerful offensive line plowing through the Pats' front seven. Picture Fred Taylor and Maurice Jones-Drew repeatedly blasting through holes inside and outside for significant chunks of yardage. Picture Tom Brady and the rest of the Pats' offense watching impatiently from the sidelines as the Jaguars march up and down the field.
"It's the best running game in the league," the Patriots' coach said of what his team will be up against in Saturday night's divisional playoff game at Gillette Stadium. Actually, the Jags have the second-best running game in the NFL and best in the AFC, but the point is the same: They run the ball exceptionally well.
"They have two great backs and they can hit the home run," Belichick said. "They can pick up a tough yard on third down or short-yardage, goal-line situations. They have a big, physical offensive line (and) use a lot of different personnel combinations -- two tight ends, three tight ends. They have a big fullback in (Greg) Jones. They run the ball on all three downs, they have good balance and they stay out of long-yardage situations, which, when you pick up those third downs then you can come back and run it again. And that's what they do."
What the Patriots don't do as well as nearly everything else they do is stop the run; they rank 10th in the league in that category. One of their linebackers, Junior Seau, is 38 years old, which is ancient for an NFL player -- especially one who is paid to avoid larger and stronger blockers and bring younger and faster ballcarriers to the ground. Even one of New England's own players, cornerback Ellis Hobbs, is on record as saying that the Patriots' defense hasn't always been as physical as it should be.
The examples are their Dec. 3 Monday night victory over Baltimore, which pushed them to the absolute brink, and their Dec. 10 triumph over Pittsburgh. In consecutive weeks, they allowed Willis McGahee to rush for 138 yards and a touchdown and Willie Parker to rush for 124 yards.
The Jaguars will set out to get Taylor and Jones-Drew above the 100-yard mark. They set out to do that in every game. In their wild-card win over Pittsburgh, 68 percent of their plays involved personnel groupings that included either multiple tight ends or a combination of a tight end and a fullback. The key, though, is center Brad Meester's ability to single-handedly get nose tackle Vince Wilfork under control. That will put greater pressure on Seau and another aging member of the linebacking corps, 34-year-old Tedy Bruschi, to shed the blocks of Jones and offensive linemen and make plays.
Yet, they don't necessarily buy the assertion that they're unable to handle larger and more physical rushing attacks. In their view, the success of McGahee, Parker, and others has more to do with members of the front seven missing assignments than being overpowered.
"You might call (dealing with a power running game) a weakness, but I think it's probably just a flaw on that particular play, where the play wasn't executed the way it needs to be executed," Wilfork said. "I think if everybody is where they need to be (and) everybody is playing the technique they need to play then we're in good shape. If not, then we're not."
"Everybody gets blocked by somebody," Belichick said. "It's just a question of how they scheme it, how they set it up and so you're going to have to defeat a block and then you're to have to tackle the guy with the ball, whoever that happens to be. It comes down to playing with good technique, playing with good leverage, doing a good job of tackling, everybody fitting in the right spot in their gaps and playing good team run defense. Six guys could do a good job. (If) one guy doesn't, that's the gap the runner hits, they have a play, so it doesn't really make any difference what the over five or six guys, or seven, however many it is that are involved in the play (do)."
What Belichick is talking about is team defense. And the Patriots have a history of playing it well, especially in the postseason.
"When you go 16-0 and see all these (great) things, people have got to find a weakness somewhere," Hobbs said. "They've got to find something to talk about. We've taken our shots, no doubt, where we've done a bad job. But if we're doing a job with the success we're having, what does that say about the rest of the league? How many bad plays have they made?
"That's why we keep it all in perspective."