Tom E. Curran • E-mail

The New England Patriots morphed in six quick seasons from beloved, plucky underdogs to detested and prickly overlords. Who could have imagined they’d go from overachieving David in 2001 to overbearing Goliath in 2007?

Everywhere but the top right corner of the country rejoiced when the Giants prevented the Patriots from going 19-0 and winning their fourth Super Bowl of the decade just 17 months ago.

But the script’s been flipped again. New England overcame the loss of Tom Brady in 2008 to go 11-5 the things that made the Pats admirable in the first place — resilience, efficiency and hyper-focus — emerged again.

So New England enters the last season of a decade they owned — five AFC Championship appearances, four Super Bowl appearances and three Lombardis — as a favorite trying come back from down under. It’s a fascinating dynamic.

But the notion that the 2009 edition will tend to unfinished (and interrupted) business from 2007 just because Brady’s back from his blown left knee misses the point that the Patriots have been drastically revamped.

Fifty-one of the 86 players on the Patriots July 1 roster were not part of the organization in 2007. The coaching staff’s undergone plenty of turnover as well with offensive coordinator Josh McDaniels leaving for Denver being the most obvious. Personnel guru Scott Pioli’s gone to Kansas City.

How well the Patriots meld the new parts with the old will determine whether they can approach the historic 2007 level when they became the first team to go 16-0, scored a record 589 points and 75 touchdowns and saw Brady and Randy Moss set the season records for touchdown passes and touchdown catches (50 and 23, respectively).

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If they have any hopes of approaching that level, the defense must improve. The Patriots ranked 31st in red zone defense in 2008, allowing touchdowns 67 percent of the time when opponents got inside their 20. They were also 26th in third-down conversion defense. Opponents converted 44 percent of the time.

Defense is where the biggest offseason changes took place, particularly in the porous secondary. The Pats added free agent corners Leigh Bodden and Shawn Springs and drafted UConn cornerback Darius Butler with the 41st overall. Add to the mix 2008 draft picks Jonathan Wilhite and Terrence Wheatley and the Pats have a completely new set of cover guys.

New England lost some swagger and attitude in the secondary with safety Rodney Harrison retiring, but it remains high on James Sanders and Brandon Meriweather. Oregon safety Patrick Chung gives them a promising young defender.

With the Bills adding Terrell Owens, the Dolphins bellowing about the progress of wideout Ted Ginn and the Jets adding a gunslinger in Mark Sanchez, New England’s pass defense is going to be under the gun all season.

Meanwhile, another stalwart of the Pats defense, Mike Vrabel, was sent to Kansas City along with Matt Cassel, meaning that group is going through a shift as well. They need to muster a more explosive pass rush but they found a gem in Jerod Mayo, the 2008 Defensive Rookie of the Year. The return of Adalius Thomas, who was starting to hit his stride when he got injured last season, should help. On the defensive line, the Pats remain one of the NFL’s best with Ty Warren, Vince Wilfork and Richard Seymour.

Of course, if the Pats average 37 points a game as they did in 2007, you and I could play corner for them and they’d still win 10 games.

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If Tom Brady’s knee holds up.

So far, Brady’s blazed through every checkpoint since January. Time lost to an infection that set in soon after the October surgery has been made up and Brady’s now ahead of schedule and performing without physical limitation.

Training camp is the next hurdle. When the veterans report to training camp on July 29, New England will use two-a-day practices for the first week. Brady will be tested early (though he will likely rest for several of them). How he responds to that next-level exertion and the pass rush of opponents in preseason games is going to be watched carefully.

But he has new toys. The Patriots added running back Fred Taylor, tight end Chris Baker and wideouts Greg Lewis and Joey Galloway to a skill group that already included Randy Moss and Wes Welker.

In a division with the vastly improved Dolphins and two other teams — the Jets and Bills — pushing their chips into the middle of the table this season, the competition in the AFC East should be fascinating.

And the question that needs answering is whether a new-look Patriots team will produce the same kind of results the NFL’s become accustomed to.

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