The only downside to the league having eight divisions is the difficulty of spreading 96 divisional games over a 17-week schedule.
Divisional games create rivalries because so much is on the line. That's why Week 4 is a treat. Nine divisional games highlight the schedule.
Week 4 gives everyone the chance to see if the Eagles really knew what they doing in dealing Donovan McNabb to rival Washington. The AFC East and AFC North races should be more defined after this week.
Here are the 10 best highlights and trends of the week:
1. The return of McNabb: Does Eagles management look like geniuses after a 2-1 start in which Michael Vick is perhaps the league's hottest quarterback and the Redskins are 1-2 with McNabb? Sometimes, it pays to be more lucky than good. The Eagles' plan was to trade McNabb and develop Kevin Kolb, but the education was stalled when Kolb suffered a concussion in the opener. Vick came off the bench and has been on a 10-quarter lucky streak, whipping the defenseless Lions and Jaguars and catching the Packers' defense with only three healthy linemen. Can it continue? Over the past couple of weeks, the Redskins' 3-4 defense hasn't been able to stop anyone through the air. Redskins defensive coordinator Jim Haslett loves to blitz, but here's the danger: ESPN Stats & Information points out Haslett may be ill-advised to blitz a defensive back, something the Redskins have done against 28 percent of opponents' passing plays this year. Vick has a 132.8 quarterback rating against secondary blitzes, third behind Peyton Manning and Drew Brees. On the flip side, the Eagles are the best team with the secondary blitz, holding foes to six completions in 19 attempts for 9 yards and a 1.3 quarterback rating. Aside from just the strategy, though, this should be quite a scene. McNabb led the Eagles to the playoffs eight times in 11 years and had them taste the thrills of five conference championship games. Will the fans cheer or boo his return?
2. Joe Flacco versus Steelers defense: Like the Ravens' defense, the Steelers' D plays its best when the offense pounds out a power running attack, giving the Steel Curtain time to regain its breath for more disruptive plays. This will be Flacco's fifth regular-season game against the Steelers, and he knows what to expect. He's 1-3 against them in those games, all determined by a seven-point or less margin. His only victory over the Steelers was a 20-17 home win last year in which Dennis Dixon filled in for Ben Roethlisberger. Charlie Batch gets the start for Pittsburgh on Sunday and everyone figures this to be a low-scoring game. Flacco has had a rough start against an early schedule littered with tough defenses. His completion percentage is 54.6 and his quarterback rating is 66.3. Despite the 3-0 start, the Steelers can't afford to let the Ravens win this home game and give Baltimore the chance for a sweep when the teams meet again Dec. 5.
3. Saints on the rebound: On paper, the Panthers-Saints game should be a blowout. This is Jimmy Clausen's second start and Saints defensive coordinator Gregg Williams will be at his devious best coming up with blitz packages to disrupt him. The Panthers' defense is handcuffed because it's still trying to figure if it has a pass rush minus Julius Peppers and blitzing isn't much of an option. Carolina's best strategy might be to stick with its base defense. According to ESPN Stats & Information, Drew Brees is averaging only 6.6 yards an attempt and has a 74.4 quarterback rating against base defenses. For what it's worth, Panthers coach John Fox has won seven of his past nine games against the Saints.
4. A big division within divisions: Although there are a couple of marquee divisional matchups, there might be a few duds if history repeats itself. The Seahawks, for example, take a 10-game winning streak against the Rams into the Edward Jones Dome. On the plus side for the Rams is the play of rookie quarterback Sam Bradford, along with the fact the Seahawks struggle on the road. (Seattle has lost eight of its past nine road games.) On the downside is running back Steven Jackson, who could miss the game with a groin injury, hurting Bradford's chances of taking advantage on easier second-down plays. The Green Bay Packers have a nine-game winning streak against the Detroit Lions. The Colts play in Jacksonville and lead the series 14-4; they've also won five of the last six against the Jags. Adding to the intrigue is the coaching seat that is getting warmer for the Jaguars' Jack Del Rio and the even hotter seat for struggling quarterback David Garrard, who has five interceptions and a puny 6.1 yards per attempt mark. The Jaguars claimed ex-Bill Trent Edwards, who is a option to replace Garrard later in the season.
5. AFC East shuffle: After Monday night, a quarter of the AFC East's 24 divisional games will have been played. By then we should know if the Miami Dolphins are along for the ride in the playoff race. The Dolphins host New England, and if they lose, they will be 1-2 in the division with two home losses. Although that wouldn't officially make the AFC East a two-team race between the Jets and Patriots, it will be hard for Chad Henne to go on the road and pull out wins in New England and New York later in the season. I see a Jason Campbell scenario developing with Henne. The Dolphins' coaching staff manages close, low-scoring games. That's what Campbell had in Washington under Joe Gibbs and Jim Zorn. In Campbell's 52 starts, he was 17-22 in games determined by eight points or less. Henne is 8-4 in similar close games in his 16 starts as a Dolphin. The downside to managing close games is the other quarterback is one drive away from winning, and when that quarterback is Tom Brady, it's a problem. Buffalo has gone 2-10 in the division the past two years. The Jets have won three of the past four from the Bills.
6. What's wrong with Carson Palmer? The Bengals' QB, on my list of elite quarterbacks, has looked like quarterback lite in the first three games. His completion percentage is 56.6 percent (it's 62.9 for his career) and he averages only 5.8 yards per attempt, 29th in the league. Last week against the Panthers, he could have thrown seven interceptions if Panthers defenders could catch the ball. Cleveland, the Bengals' opponent Sunday, has the league's 12th-ranked passing defense.
7. The hot seat moves from the Windy City: No coach was on the hot seat more than the Bears' Lovie Smith. A 3-0 start has turned down the temperature and made the Bears, who play the Giants on Sunday night, a legitimate playoff contender. The hot seat focus now shifts to New York, where Giants coach Tom Coughlin is under fire. The Giants are making more mental mistakes than big plays. New York, known as one of the best-coached teams in the NFL, looks undisciplined at times. And here are interesting passing numbers: According to ESPN Stats & Information, Eli Manning is throwing well, completing 31 of 43 passes for a 10.6-yard average on throws outside the numbers on the field. Inside the numbers, though, he's 36-for-59 for a 6-yard average and six interceptions. Not good.
8. The Bolts with less electricity: The Chargers, who play the Cardinals on Sunday, said no to trade requests for wide receiver Vincent Jackson and no to his demands for a big contract. But Philip Rivers has changed his game because of Jackson's absence and that of Marcus McNeill at left tackle. According to ESPN Stats & Information, Rivers, one the league's best riverboat gamblers, has thrown only 10 passes that have traveled more than 20 yards, completing four for 187 yards. After three games last season, he was 16-for-28 for 563 yards and five touchdowns on passes that traveled more than 20 yards. Good news: McNeil, who held out, is eligible to return Oct. 17 against St. Louis.
9. Singletary's problems are multiple: It had to pain 49ers coach Mike Singletary, stunned after an 0-3 start, to watch the tape of the loss to the Chiefs and then decide to fire offensive coordinator Jimmy Raye. The timing couldn't be worse. The 49ers must make a cross-country trip to play at 1 p.m. ET against the talented Falcons. Usually, it takes a West Coast team a half to get their body clocks squared away. (NFC West blogger Mike Sando has a good breakdown here.) An 0-4 start could put the snooze button on the 49ers' season.
10. Bottom-feeders: When you look at it closely, the Broncos haven't played poorly. Their defense isn't all that bad and quarterback Kyle Orton is playing at a Pro Bowl level. But if the Broncos lose to the Titans in Nashville, they will drop to 1-3 and would have lost 11 of their past 14 games. The Raiders-Texans game will feature a pretty good running back matchup with Darren McFadden facing Arian Foster. The Raiders are tied for second in the league in defense, allowing only 261 yards a game. That number could be carved up by a Texans team that is putting up 407 yards a game.
John Clayton, a recipient of the Pro Football Hall of Fame's McCann Award for distinguished reporting, is a senior writer for ESPN.com.