FOXBOROUGH, Mass. -- There was a time when some were asking whether the Patriots could win when it mattered most in spite of their defense.
After they allowed the second-most passing yards in NFL history in 2011, holes appeared to exist in the secondary leading into 2012, and neither of the team's double-digit sack producers from 2011 returned in the offseason.
Cautious optimism sprouted after a strong couple of weeks to open the 2012 regular season, but a Week 3 loss to Baltimore in which Ravens quarterback Joe Flacco threw for nearly 400 yards had many taking a trip down memory lane.
The concerns relating to the defense's allowing long passing plays down the field climaxed during a Week 6 loss to Seattle: A 46-yard touchdown throw to a wide-open Sidney Rice in the closing minutes of the game left the Patriots' secondary looking for answers.
And it was at that time that Bill Belichick and his staff dug deeper for answers, notably the transition from cornerback to safety by Devin McCourty. The moves have paid off over time.
"I'd like to think we improved," Belichick said of defending against the big plays. "We certainly worked on it. We made a couple changes after the Seattle game, but not that we didn't work on it before but we kept working on it more. I think overall the results were better."
The McCourty switch was tied together by inserting rookie cornerback Alfonzo Dennard into a starting role, where he has remained since.
But the improvements weren't immediate, as the Patriots allowed Mark Sanchez and the Jets' passing offense to surpass 300 yards in Week 7.
Nonetheless, foundations were being set and the shift was under way.
The process of improving the defense was expedited by the acquisition of talented cornerback Aqib Talib at the trade deadline.
Talib's coverage skills allowed the Patriots to alter the way they played in the secondary behind him, and can likely also help explain the team's increased reliance on pressuring the quarterback.
Over the first 10 weeks of the season plus Talib's first game with the team and Week 17, in which he was active but did not play, the Patriots brought five or more rushers on just 19.1 percent of all passing downs, 30th in the NFL.
That figure ballooned to 35.7 percent from Weeks 12 to 16, during which Talib was an integral part of the defense's game plan.
Having a more capable secondary to stick to receivers in man coverage opens the door for a front seven to send pressure, and the addition of Talib has undeniably improved the secondary.
According to ESPN Stats & Information's John Parolin: "Since the Talib addition, the Patriots have allowed opposing quarterbacks a 51.1 completion percentage, three touchdowns and five interceptions with at least five pass-rushers (73.6 completion percentage, four touchdowns and no interceptions in first nine games)."
In fact, the entire defense has grown over the past six weeks, as only three teams have allowed fewer points per game in that time than the Patriots (17.7).
That compares to 22.5 during the first 10 games of the season, a figure that ranked 16th overall.
The Patriots have also surrendered more than 40 fewer yards per game, fewer points per drive, and held opponents to touchdowns on a much lower percentage of drives during the six-game sample size.
Beyond the pass defense, Belichick attributed the improvement to a number of factors.
"I think it's a combination of a lot of things," he said. "I don't think it's any one thing, one player, one call, one thing. Defense is team defense. Part of it is coaching and scheme and putting the players in the best chance they have to be successful. It's pass defense, it's pass rush, it's run defense to create longer yardage situations, it's pressure coverage, it's a little bit of everything."
And not only are the Patriots making strides in areas that were previously limitations, they're building on the strengths that were already in place.
The defense produced 16 sacks over the final six weeks of the season -- seven of which came in the season finale -- despite missing Chandler Jones and Jermaine Cunningham for strings of games during that time (and recently playing most of Week 17 without Rob Ninkovich).
But in perhaps no area has the Patriots' defense made its mark in 2012 more than turnovers forced. Only one team, the Bears, forced more turnovers than the 41 generated by the Patriots' defense in 2012, including an AFC-best 20 interceptions.
In critical situations in games -- whether it was two interceptions from Patrick Chung in Week 16 against Jacksonville, or a pair of forced fumbles from Ninkovich in a Week 5 win over the Broncos, or three defensive touchdowns scored in a two-game stretch to close out November -- the Patriots' defense has shown itself to be game-changing.
It was evidenced in pivotal plays throughout the season, and can be reinforced by examining the season-long body of work through a relevant statistical lens.
While Belichick on Wednesday warned against giving too much credence to statistics, there are two that he cares about.
"The most important one is wins, the next most important one is points," he said.
With a late-season resurgence contributing to a 12-win season, the Patriots finished 2012 ninth in total points allowed at 20.7.
Their defense has undergone growing pains in 2012. There were times when it looked to be the same defense that endured woes in 2011. But over the course of the season, and specifically during the final six weeks, the Patriots' defense has shown dramatic improvement.
That improvement stands as reason to no longer question the defense as a potential problem the team must overcome to reach its ultimate goal.
This defense is part of the solution.
Field Yates covers the Patriots for ESPNBoston.com.