Bill Barnwell speaks with Scott Van Pelt about the high-level play from both Aaron Rodgers and Matt Ryan heading into the NFC Championship Game and what the Steelers need to do to upset the Patriots for the AFC title. (3:17)

FOXBOROUGH, Mass. -- Some view the glass as half-full, while others see it as half-empty.

Apply that line of thinking to the New England Patriots' defense, and it goes something like this: Some say the unit still has something to prove because it hasn't been tested by the game's top quarterbacks, while others look at the caliber of running backs the D has slowed down this season and say, "What more could you ask for?"

The haven't-faced-top-quarterbacks story has been thoroughly analyzed at this point leading into Sunday's AFC Championship Game against the Pittsburgh Steelers, whose QB, Ben Roethlisberger is right there with Seattle Seahawks signal-caller Russell Wilson as the best the team will face in the passing game this season and postseason.

In last week's Patriots playoff win, Houston's Lamar Miller wasn't the first running back to be gobbled up by Dont'a Hightower and the New England run defense. Elsa/Getty Images

Meanwhile, the spotlight hasn't shined as brightly on how the Patriots' run defense, led by defensive tackle Alan Branch and linebacker Dont'a Hightower, has put the clamps down on some of the game's best rushers. The Patriots will need to be at their best again on Sunday against Le'Veon Bell.

The defining stat of the week: The Patriots haven't allowed a rusher to gain 90 or more yards in any of their past 24 games, while Bell has hit that mark in each of his past eight games. Furthermore, the Patriots haven't allowed a rushing touchdown since Oct. 30, while Bell has nine over that span.

It's the classic matchup of strength vs. strength.

Here are some of the numbers of No. 1 running backs against the Patriots this season:

David Johnson: 16 carries, 89 yards

Jay Ajayi: 5 carries, 14 yards

Lamar Miller: 21 carries, 80 yards

LeSean McCoy: 19 carries, 70 yards

Isaiah Crowell: 13 carries, 22 yards

Jeremy Hill: 13 carries, 38 yards

Le'Veon Bell: 21 carries, 81 yards

Carlos Hyde: 19 carries, 86 yards

Matt Forte: 13 carries, 27 yards

Todd Gurley: 11 carries, 38 yards

Jay Ajayi: 16 carries, 59 yards

New England's run defense hasn't always been airtight, with Buffalo's Mike Gillislee and Seattle's C.J. Prosise finding some creases to exploit, and it's also notable that the Patriots' ability to get an early lead has forced teams out of some running situations earlier in games. But overall, the Patriots have been able to achieve their goal of building a wall at the line of scrimmage, accounting for gaps and tackling well at all levels against some of the NFL's best running backs.

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Bell comes to town with a unique style; he'll often wait behind the line of scrimmage for a crease to open before exploding through it, so New England defenders have stressed the importance of discipline in Sunday's AFC Championship Game.

It's the latest stiff test in a season full of them. To this point, the run D has pretty much answered them all.