By Dan Durkin-

(CBS) It’s nearly unfathomable to think that 181 wins, 11 division titles and three Super Bowl trophies can be traced back to a sheared blood vessel. It’s true, though. The crushing hit New York Jets linebacker Mo Lewis put on then-Patriots quarterback Drew Bledsoe back in Week 3 of the 2001 season changed the course of history for the New England Patriots.

Lost in the legend is the fact just six months prior to suffering the life-threatening injury, Bledsoe inked — at the time — the richest contract in NFL history, a 10-year $103-million dollar deal that would’ve made him a free agent in 2010. Patriots coach Bill Belichick turned the team over to Tom Brady, a second-year player who 16 months prior watched 32 teams pass on him five times — some of them six —  and heard Chad Pennington, Giovanni Carmazzi, Chris Redman, Tee Martin, Marc Bulger and Spergon Wynn have their names called ahead of him.

The rest is history. Belichick and Brady have become the NFL’s winningest coach/quarterback combination (171 wins) and perennial championship contenders.

Despite being undermanned at the receiver position, enduring some spotty pass protection and playing without two of their top players — linebacker Jerrod Mayo (patellar tendon) and running back Stevan Ridley (ACL, MCL) — the 2014 Patriots protect the football and take it away from their opponents (plus-nine turnover differential) and are in their familiar perch atop the AFC East with a 5-2 record.

Belichick has been coaching in the NFL for 39 years straight. Known primarily as a defensive mind, he has coached in all three phases. Long before the league became popularly known as the week-to-week affair it is, Belichick was coaching it that way. No other coach of recent vintage has shown more of a willingness — or capability — to reinvent his team to be what it needs to be at that moment to maximize its chances of winning the game than Belichick.

Both Belichick and Brady adjust their focus to the micro, deftly counterpunching their opponent play to play to wear them down. By utilizing a basic framework of concepts and common terminology, the Patriots offense runs plays at a fast rate — seventh-most in the league this year — and simplifies both the route combinations for the receivers and the reads for the quarterback.

They lack weapons who can consistently beat man coverage on their own, so pre-snap, they rely on motions and alignments to get their receivers free releases. And post-snap, they heavily utilize option routes that allow the receiver to read the leverage of his defender to determine the direction of his route at the top of the stem.

Since taking over as the starter, Brady has guided the Patriots to a top-10 scoring offense finish in all but one season, and they’re on pace to finish there again, as they currently rank seventh. They’ve changed their stripes numerous times to best fit the available personnel, and this season, they’re running an up-tempo attack primarily out of 12, 11 and 21 personnel groupings.

Given that Brady is still developing chemistry with his only true outside receiving threat, first-year Patriot Brandon LaFell, New England is utilizing its run game to set up play-action shots down the field. Brady’s most trusted weapons remain receiver Julian Edelman and tight end Rob Gronkowski, who rank first and second on the team, respectively, in targets.

Gronkowski seems to be getting closer to being fully recovered from ACL surgery this past January. He leads the team with four touchdowns and is averaging 10 targets per game over the past three weeks.

With Ridley out of the picture, Shane Vereen (brother of Bears safety Brock Vereen) is the focal point of the running game, which has struggled overall. However, Vereen is a versatile, dual-threat player whose best contributions will be made in the passing game, as he can consistently beat safeties and linebackers both from the backfield and split out.

In their first game without Ridley (last Thursday night against the Jets), the Patriots passed the ball 70 percent of the time. Given the extra time to prepare for Sunday’s game, it’s safe to assume more running schemes will be devised to test the Bears’ defensive front, which has been susceptible to misdirection plays due to overpursuit.

A staple of the Patriots offense is play-action off of their stretch run plays. Given the fact that Bears’ linebackers were frequently exploited last weekend by getting caught with their eyes in the backfield and losing their coverage responsibility, Brady will certainly pull their strings.

Reliance on reliable and sturdy offensive line play isn’t unique to the Patriots offense. Offensive coordinator Josh McDaniels schemes quick decision-making and shorter drops in his passing attack, which may make it seem like pass protection wouldn’t need to be at such a premium, but it is. Early on in the season, the unsettled offensive line sped up Brady’s decision-making, which led to errant passes and the offense operating out of sync, as route combinations didn’t have time to properly unfold.

The Patriots traded long-time stalwart left guard Logan Mankins before the season and shuffled the deck a few times afterward, sometimes during the game. The group of five they’ve now settled on has played back-to-back weeks, and the offense seems to be operating more efficiently.

Defensively, the biggest move the Patriots made was signing shutdown cornerback Darrelle Revis. Given their preference for man coverage, Revis is a natural fit. He can defend half of the field on his own and doesn’t require safety help over the top, which gives defensive coordinator Matt Patricia flexibility in how he utilizes his safeties in his hybrid defensive scheme.

Strong safety Patrick Chung has returned to New England, where he’s heavily utilized as box player in run support and can play robber techniques in the intermediate passing zones. Free safety Devin McCourty patrols over the top to keep a cover on the defense and has fluid hips and play recognition to leave his centerfield landmark and quickly break to the hashes.

Losing their top pass rusher, defensive end Chandler Jones, for a month with a hip injury is a big blow to the defense. Jones (selected two spots after Bears linebacker Shea McClellin) has developed nicely as a pliable edge rusher who plays with leverage and length to bend the edge. Jones’ counterpart, Rob Ninkovich, is primarily a run stuffer but is second on the team in sacks (four).

With Mayo out for the season, the Patriots are without their veteran presence at the second level to set the front. However, young prospects in Dont’a Hightower and the uber-athletic Jamie Collins are progressing well within the scheme, particularly in pass coverage.

Opposing quarterbacks are averaging a league-low 208 passing yards per game and an 85 passer rating, which is the eighth-lowest in the league. The Patriots’ cornerbacks press at the line and challenge releases to disrupt the timing of pass plays. However, opponents have had success running the ball, particularly to the defense’s right side.

The Patriots aren’t as dominant as they’ve been in the past, but they’re still a dangerous team, especially at home. Since 2003, the Patriots are 24-1 in October at home and have won 12 straight home games. Given what lesser quarterbacks have done to the Bears — EJ Manuel and Ryan Tannehill — and the nearly perfect performance by Aaron Roders, Brady must be anxious to get his chance against the Bears’ generous defense.

Dan Durkin covers the Bears for CBSChicago.com and is a frequent contributor to 670 The Score. Follow him on Twitter at @djdurkin.