The New England Patriots again look like one of the best teams in the league. They are 4-0 after their first four games. Unlike some of their undefeated brethren, they are winning in dominant fashion. They have outscored their opponents by 73 points, most in the NFL, and have held a three-score lead in the third quarter of every game.

This is far from the first great-looking Patriots team we have seen in the Bill Belichick and Tom Brady era. Just how does this team compare to those other great teams? How is it the same? How is it different? What do those teams suggest about how likely this team is to keep up its greatness?

Comparing Past Patriots Teams Through Four Games

This Patriots team is really good, even by the standards of past Patriots teams. Table 1 has the basic details, including comparisons to every New England squad over the past decade that has earned a first-round bye.

Table 1. Patriots Bye Teams Through Four Weeks, Conventional Statistics

Season Early Record Margin Record in Last 12 Games Final Record 2007 4-0 +100 12-0 16-0 2015 4-0 +73 ? ? 2013 4-0 +32 8-4 12-4 2011 3-1 +37 10-2 13-3 2010 3-1 +35 11-1 14-2 2012 2-2 +42 10-2 12-4 2014 2-2 -10 10-2 12-4

This is just the third unbeaten team through the first quarter of the season. The unbeaten 2013 Patriots were a normal unbeaten, like this year’s Carolina and Denver squads, with a number of close wins — 2007, though, was on a different level. This year’s Patriots has taken big leads in every game, but allowed Pittsburgh and Buffalo to narrow the gap for eventual one-score wins. In 2007, by contrast they won each of their first four games by at least 21 points.

Advanced stats concur with the basic details of the table above. Here are those same squads as of the same time in the season by Football Outsiders’ DVOA metric.

Table 2. Patriots Bye Teams Through Four Weeks, Advanced Statistics

Season DVOA Through 4 Games (rank) Final DVOA (rank) 2007 73.4% (1st) 52.9% (1st) 2015 55.9% (1st) ? 2013 13.4% (7th) 18.9% (5th) 2011 29.1% (2nd) 22.8% (3rd) 2010 32.5% (1st) 44.6% (1st) 2012 31.6% (3rd) 34.9% (3rd) 2014 -5.8% (23rd) 22.1% (4th)

The 2015 team comes out roughly equidistant from the ridiculous greatness of the early season 2007 Patriots and the more normal greatness of the 2010, 2011, and 2012 Patriots. These teams all had flaws (the 2012 Patriots were just 2-2), but each had pretty decisively defeated a couple opponents.

What Makes This Patriots Team Different

It probably comes as no surprise the 2015 Patriots have the best offense in the league through the first five weeks of the season. It should not have. This is actually the fifth time in the seven seasons we are considering they are the best through four games. But football is about more than having a great offense. What makes this Patriots team better than some of the editions from the recent past is their defense.

Table 3 shows the same Patriots teams and their DVOA through their first four games for each of the three phases of football.

Table 3. Patriots Bye Teams by Offense, Defense, and Special Teams DVOA Through Four Weeks

Season Offensive DVOA (rank) Defensive DVOA (rank) ST DVOA (rank) 2007 46.6% (1st) -20.9% (3rd) 5.9% (9th) 2015 38.1% (1st) -8.7%(9th) 9.1% (3rd) 2013 2.6% (15th) -5.0% (14th) 5.8% (4th) 2011 38.4% (1st) 11.3% (27th) 2.0% (11th) 2010 32.2% (1st) 13.4% (27th) 4.6% (4th) 2012 33.2% (1st) -1.7%(18th) -3.3% (24th) 2014 -17.0% (28th) -8.0% (10th) 3.2% (9th)

This year’s offense is good, no question, but it was just as good in 2011 and nearly as good in 2010 or 2012. The special teams unit is particularly good, but it has been good most years. What sets this Patriots team apart from most of the non-2007 squads is the defense, which is the best it has been.

Just how good the defense has been early has been a surprise, since it seemed reasonable to expect the Patriots’ defense to decline with the losses of Darrelle Revis, Brandon Browner, and Kyle Arrington. One of the league’s best pass-rushes has helped cover up for the revamped secondary, and the pass defense on the whole has been outstanding. And, no, Brandon Weeden is not too big a factor; looking just at the other games, the Patriots still have a top ten pass defense.

What It Means for the Rest of the Season

Looking at Table 2, the good news is most Patriots teams have actually gotten better as the season goes on because Bill Belichick is one of the best coaches in the league and learns and adapts more to what that year’s personnel grouping does best.

The past 26 seasons of DVOA suggest, though, that it is difficult to be powered too much by one unit, and the best teams are outstanding in all three phases. The 2007 team is a great example of that. The offense was outstanding all year, but the defense declined. For that team to finish 16-0 required a number of close calls, and they faltered when the offense put up just 14 points in the Super Bowl.

The best team since 1989 by DVOA is actually 1991 Washington. Joe Gibbs’ last Super Bowl outfit was not incredibly dominant in any single phase, but instead had the league’s best offense and special teams and the third-best defense.

The key for just how good this year’s Patriots can be is whether the defense can hold up for all 16 games, like last year’s unit but unlike 2007’s. The early season offensive struggles in 2013 and 2014 suggest keeping Rob Gronkowski healthy is pretty important, too. Do both of those, and another 16-0 season is on the table.