Tom Brady's biggest weakness has made the Patriots vulnerable in one area

The New England Patriots are entering their biggest test of the season on Sunday when they play the Denver Broncos in the AFC Championship in Denver.

The Patriots' 27-20 win over the Kansas City Chiefs in the divisional round of the playoffs saw the Patriots execute their most vital game-plan: protecting Tom Brady.

Brady wasn't sacked and was only hit once by the Chiefs' pass rush on Saturday. That may change against the Broncos.

The Patriots have been using an alternating, revolutionary offensive line all year, but as MMQB's Jenny Vrentas writes, there's one area where they're vulnerable to attack from other teams, and it happens because of Brady's only weakness: his lack of mobility. From Vrentas:

Opposing coaches and players will tell you that the Patriots' most talented linemen are their tackles, and that Brady is most vulnerable when you take advantage inside and pressure him up the middle. He's not going to flee the pocket like Russell Wilson, so edge rushers flying past him aren't a concern. But when there's push up the middle and he can't step up in the pocket, the edge guys can bring him down. And pressure in his face, theoretically, can interfere with his quick-timing passing game. The Chiefs didn't get that push up the middle, nullifying their speed guys on the edge.

Former Patriots center Dan Koppen told Vrentas of the Chiefs game, "I think inside, they did a great job blocking and keeping that pocket firm, running the outside guys by him, where Tommy doesn't care about them. If he is able to step up into the pocket, and he's comfortable throwing the ball, it's usually a long hard day for any defense to go against."

But the Patriots' vulnerability on the inside remains a problem. As Vrentas notes, teams with good inside rushers gave the Patriots trouble, as seen in games against the Jets, Bills, and the Patriots' first loss of the season, the Broncos.

Rushing from the outside is the easiest path to a quarterback for defenses. The Patriots have done a solid job fortifying that route to keep Brady safe. But it benefits both sides - Brady doesn't plan to scramble, so if he can stay in the pocket, he doesn't care about edge rushers. For defenses, though, if they can bring pressure inside, then they force Brady out of his comfort zone, either making him scramble or running into those edge rushers.

Against the Broncos in Week 12, as the pocket collapsed on Brady, he tried to step up, only to be brought down by Von Miller:

Spotrac's positional spending map seems to verify that the Patriots, at least financially, have placed more importance on protecting Brady on the outside than on the inside. For as unbeatable as the Patriots can seem at times, their offensive line isn't one of their greatest strengths. According to Football Outsiders, the Patriots ranked 18th in pass protection, giving up 38 sacks.

The Broncos, meanwhile, were the best defense in the NFL, with a league-leading 52 sacks. Getting into a shootout against the Patriots won't work for the Broncos, but they possess their own advantage in their ability to get to Brady.