What did we learn in the first quarter?

We've reached the end of the first quarter of the NFL regular season. Two teams are undefeated. Four still haven't won a game. Two aren't living up to their outspoken expectations. There's a Hasselbeck revival in Tennessee, a Welker emergence in New England and a Newton explosion in Carolina.

There has been an unexpected shift in the NFC East, steadiness in the NFC South, a surprise challenger in the AFC East and a potential changing of the guard in the AFC South.

It has been only four weeks, but here's a look at a few truths that have emerged from the first four weeks of the season.

The Lions are for real: Yes, I know. This isn't breaking news. But think about it for a minute: Detroit really is a player, the luckless Lions, the franchise that was everybody's easy victory for a decade.

The last time Detroit was talking about a Super Bowl was 2006, and that was only because the city was hosting the event. The Lions haven't won a division title since 1993, and they haven't won a playoff game since 1991.

This could be the year, not for a Super Bowl title or even a divisional title, but the wild card is a possibility. The Lions are 4-0, a record matched only by the defending Super Bowl champion Green Bay Packers, and anything is possible at this point. That is truly unbelievable, and beautiful, and fun.

And let's face it. The NFL needs more Megatron. We all need more Megatron.

The Packers are better than last year, and that's scary: No one is pounding the undefeated drum just yet, but give it a few weeks. The Packers play what should be a tough game Sunday night at the Georgia Dome against Atlanta. After that, they host St. Louis and play at Minnesota before taking their bye in Week 8.

It is not inconceivable that the Packers will be 7-0 entering November. If that's the case, the drumbeat will begin.

Look who is up there with the big three: There are four quarterbacks with double-digit touchdown passes. Three are easy to figure: Tom Brady (13), Aaron Rodgers (12) and Drew Brees (10). The fourth? Detroit's Matthew Stafford, who has 11.

When Eli Manning said in the preseason that he believed he was among the elite quarterbacks in the league, he probably wasn't factoring in Stafford, who is third in touchdown passes and seventh in passing yards and is completing a respectable 62.1 percent of his passes.

Manning has had a solid start, as well, with eight touchdowns and just two interceptions. But the top five is a tough list to crack: Brady, Rodgers, Brees, Stafford and Tennessee's Matt Hasselbeck. And yes, Philip Rivers and Cam Newton, we see you.

Wes Welker is more than just a slot receiver: He leads the league with 40 receptions (13 more than No. 2 Jason Witten) and 616 receiving yards. With 154 yards per game, he is one of three players (Pittsburgh's Mike Wallace and Carolina's Steve Smith are the others) to average at least 100 yards receiving over four games. Welker has 11 catches for at least 20 yards and 29 for first downs.

He has been nothing short of magnificent.

Don't forget about San Diego: The Chargers are 3-1! The Chargers are 3-1! The Chargers are 3-1!

Sure, their three wins came against opponents (Minnesota, Kansas City and Miami) that are 1-11 through the first four weeks, but San Diego can only play the schedule it was given, and, for the first time under Norv Turner, the Chargers are 3-1. For a team that typically starts slow and finishes strong, that's saying something.

A quarterback's worst nightmare isn't DeMarcus Ware; it is the retired former player: The old guys are sacking their younger brethren with remarkable frequency these days, whether it's Joe Namath criticizing Mark Sanchez and the underperforming Jets offense (not that he was wrong), Joe Theismann saying Donovan McNabb has been exposed as inaccurate (not that he was wrong, either) or Deion Sanders piling on Tony Romo (he, too, has a point).

Then there was Brett Favre, who obviously has tired of retirement. Favre told the Atlanta radio station 790 the Zone that he wasn't surprised Rodgers delivered a Super Bowl win to Green Bay, only that it took him so long. Knowing Favre, it wasn't exactly a compliment. Plus, Favre said this about Rodgers: "He's got tremendous talent; he's very bright; and he got a chance to watch and see successful teams do it right."

Translation: Me, me, me, it was all because of me. Not that Favre is the only one to act like that.

We miss you, Carson Palmer: I'm quite sure that life is grand in California. Beautiful weather. Beautiful people. Mike Brown will never admit that he misses you, but the rest of us do. Come back. Just be sure to wait a few more months.

NFL, or Not For Long: There are three coaches whose seats are getting hotter by the week: Jack Del Rio, Tony Sparano (whose job just got tougher with the news that Chad Henne will miss the rest of the season) and Todd Haley. There's one, Gary Kubiak, whose seat has cooled off but might warm back up if the Texans don't make the playoffs.

And then there is one whose seat never seems to warm up: Andy Reid.

Eagles fans have been calling for Reid's head after a 1-3 start and the continuation of the mistakes of years past. What is the definition of insanity? For Philadelphia fans, it is the head coach mismanaging the clock, calling trick plays when conventional ones would do, not punching the ball in from the 1-yard line, taking responsibility for another loss and vowing to put his players in position to do better. Reid's hiring of his longtime offensive line coach as the defensive coordinator isn't going over so well, either.

Philly Fan is understandably edgy, but Reid isn't going anywhere. Jeffrey Lurie prides himself on being a reasonable, rational person. He's not going to make a rash decision based on four games. He probably wouldn't fire Reid even if Philadelphia missed the playoffs this year. Lurie likes stability and consistency.

For Reid, NFL stands for Never Fear Losing his gig.

Peyton Manning needs to get out of the coaches box: Manning has watched the past two games with the coaches in the press box. He has looked a little lost, as though he might never get out. On Thursday, Manning acknowledged that he felt as awkward up there as he looked. Starting Sunday, he will be on the sideline with the rest of his teammates. Good choice.

The lockout wasn't all bad: It seems like forever ago now, but for all the contingency planning coaches did during the lockout, the elimination of minicamps and OTAs did not kill the game. In fact, it might have made it, if not better, at least more entertaining.

Consider these facts culled by ESPN's Stats & Information group:

Passing is up more than 24 yards over last year's record of 221.6 yards per game. There have been 44 300-yard games, 19 more than the next-highest total through four weeks. With an average of 22.78 points per game, teams are scoring at the highest level since the AFL-NFL merger. Leads are harder to hold on to than ever before; we've seen 16 double-digit comeback wins and nine of more than 14 points, both NFL records through the first four weeks of the season, according to Elias Sports Bureau. And there have been more close games than ever; 35 of 64 games have been decided by seven or fewer points, including 19 that were decided by three or fewer points.

Sure, there has been some sloppy play in the first quarter of the season, but overall? Not bad.

Ashley Fox covers the NFL for ESPN.com.