It wasn't a quick deterioration; it happened over a span of half a decade. The once elite Patriots defense slowly evaporated over the latter part of the aughts until it could no longer hold itself together.

In 2006, linebacker coach Dean Pees was tagged to replace former defensive coordinator Eric Mangini and, hopefully, not skip a beat. The Patriots were coming off their worst defensive season in Bill Belichick's tenure and they were trying to re-right the ship. After finishing first in points against and seventh in yards in 2003, and then second and ninth in 2004, the defense collapsed with a year ranking 17th in points against and a deplorable 26th in yards against.

It proved to be an atypical season, as the Patriots saw their post-season hopes dashed far earlier than Patriots fans believed possible. 2006 saw the departure of Willie McGinest and Matt Chatham, as well as a few additional members of the secondary, and the writing was on the fall for the impending future: this defense was getting up there in age and it needed to be rebuilt.

Defensive leaders like Rodney Harrison, Tedy Bruschi, and Mike Vrabel were in their 30s and heading towards a cliff in their career production. The secondary found itself struggling to find above-average safeties. Most importantly, though, was how dry the well ran. Between 2006 and 2008, the Patriots found a dearth of talent in the draft, adding only Brandon Meriweather, Jerod Mayo, and Jonathan Wilhite to the defense, while watching the departure of Asante Samuel, Eugene Wilson, Rosevelt Colvin, as well as a trade of Richard Seymour and the twilight season of Harrison, Bruschi, and Vrabel's career.

The cavalry wasn't coming through the door and perhaps Pees was thrust into an unfair situation. But under his watch, the Patriots league rank in points allowed slowly dropped from 2nd, to 4th, to 8th, and finishing in 5th in his final season, while the yards allowed fell from 6th to 11th. On the positive end of the spectrum, 3rd down defense improved from 42% in 2005 (and 38.8% in 2004) back to the levels of the Patriots #1 ranked 2003 defense, ranking at 36%, 33.7%, 44.2% (twilight season), and rebounding up to 36.1%.

Pees received a lot of the blame for the Patriots production, when in reality, he milked tremendous production out of aged goods and cast-offs. His final season brought in Pat Chung, Darius Butler, and Ron Brace, the first time the Patriots really tried to address the issue of their aged defense.

It was too little, too late, and yet the Patriots still improved upon their 2008 season.

But after Pees' departure in 2009, Belichick opted to control the defense in 2010 and 2011, deflecting the spotlight and the blame from the man actually calling the plays.

Enter Matt Patricia. Or, rather, watch Patricia get thrown into the fire.

2010, the Patriots fall from 5th in points against and 11th in yards allowed to 8th and 25th, respectively. They allow 47.1% conversion on third down.

2011, the defense continues to fall to 15th in points against and 31st in yards allowed, while bringing the 3rd down defense up to 42.9% conversion.

Patricia, the former college offensive lineman, hit rock bottom, as far as Patriots fans were concerned. They were forcing turnovers at an unprecedented rate, yet that seemed to be the only way the team could generate a stop. But those paying close attention could see that the potential for improvement was within reach. The Patriots focused on adding quality depth to the defense under Patricia's watch.

The youth movement went from Chung, Butler, and Brace, to include Devin McCourty, Jermaine Cunningham, Brandon Spikes, Brandon Deaderick, Kyle Love, and Dane Fletcher in 2010, Ras-I Dowling in 2011, Chandler Jones, Dont'a Hightower, Tavon Wilson, Jake Bequette, and Alfonzo Dennard in 2012, and Jamie Collins, Logan Ryan, Duron Harmon, Michael Buchanan, Chris Jones, Joe Vellano, and all of the rookies who have played a major role in the success of 2013.

The Patriots defense went from aged and over the hill to one of the youngest units in the league. Only three of the projected starters were over the age of 30 (Tommy Kelly 33, Vince Wilfork 32, Steve Gregory 31), and by the end of the season Gregory and Rob Ninkovich were the only starters over the age of 27. Hell, six of the starters are 24 or younger, which puts the 26-year-old Devin McCourty on the "elder statesman" side of the defense.The 27 year old Aqib Talib is the only remaining free agent starter on defense.

We talk about how this season might be one of Belichick's greatest achievements, with how many injuries they've faced, but this could also be considered the coming out party for Matt Patricia.

After horrendous 2010 and 2011 defensive seasons, the Patriots acquired Talib midway through the 2012 season, spending a 4th round pick for a half-season rental. While Talib wasn't anything transcendent in his first few games with the Patriots, it allowed them to take on a monumental shift in defensive identity.

Not only was the defense still trying to slide away from its 3-4 defensive fronts and back into the world of 4-3 defenses, but they also abandoned much of their zone coverage concepts in favor for more man-coverage looks.

If Belichick was the architect, Patricia was the foreman.

In Patricia's 10th season with the Patriots, and second as the official defensive coordinator, the Patriots defense has never been so reliable or impressive. Forget that they were ranked 10th in points allowed and 26th in yards allowed. Forget that they've lost four starters at the heart of the defense, in addition to roughly 9 more lost games due to short term injuries to starters. Forget the 42.7% 3rd down conversion rate, on par with the 2011 season.

Ask yourself one question: When's the last time you felt this confident in your defense?

2008? 2007? No, they're not putting their championship numbers, but do you believe in this unit?

I do. The defense kept the Patriots in the games early in the year, when the offense couldn't produce. And when the offense found its bearings, the defense had to transform and adapt to whatever players were healthy enough to take the field.

Over the first six games of the season (Pre-Rob Gronkowski), the defense held the opposition to 16.2 points per game and a 37.5% 3rd down conversion rate.

Since the final quarter of the season (Post-Gronk, post-Sealver Siliga, as well as the return of a healthy secondary), they've held the opposition to 19.8 points per game and a 38.2% conversion rate.

Throw out the mid-season defensive flux, when Aqib Talib was sidelined with a hip injury, the Patriots didn't have a viable replacement for Tommy Kelly or Vince Wilfork, and when Dont'a Hightower was playing out of position and out of his element. That unit surrendered an atrocious 27.3 points per game and a mortifying 50.5% third down conversion rate.

This is not that defense. This is a defense that once was lost, now is found, and Patricia is the bearded shepherd that will guide them through to the end.

This is a defense that is built by the hands of Belichick, yet undeniably molded and shaped by Patricia.

And the biggest challenge is still to come.

Patricia will take his duct-taped unit and square off against the most explosive offense in the history of football. This isn't the same team that somehow managed to walk away with a victory in week 12. This unit is 33% better. This unit has fluctuated from a top 5 unit, down to a bottom 5 unit, and has made its way back into the top 5.

Patricia has grown from a questionable heir who inherited a broken defense into a top caliber defensive coordinator with one of the youngest units in football.

This has been Patricia's year, just as much as it has been Belichick's and Brady's. He's proven that he's able to take his defense to the top of the league, no matter the odds he's faced, and he'll be charged with the most important job of the season, through this point.

And without question, Patricia is clearly the right man for the job.