Now come two games that might deliver a peek into their second half: contests at Cincinnati and at Denver.
For all the Chargers have accomplished this year -- co-leaders of the AFC West -- there are still some items to check off.
No. 1 is winning an away game against a playoff-caliber team.
The Chargers have two roadies in their pocket, but neither victory required crossing state lines. Wins in Oakland and San Francisco level their road mark at .500. But what's more telling are the losses at Baltimore and Kansas City.
So that's what makes Sunday's game against a wobbly Bengals squad so important. If the Chargers really are one of the elite teams, they need to prove it.
Not in Oakland. Not in San Francisco. But in Cincinnati. Then at Denver.
"We got what we needed to get done as far as the two home games," quarterback Philip Rivers said. "We're kind of in a stage where we're getting on that roll and we need to keep it going. We need to win a tough game on the road."
But the Bengals don't figure to roll over. They are getting blasted in all circles as underachievers, they are pointing fingers at each other and they are absorbing all the arrows that come with a disappointing first half.
The Bengals, though, aren't dead yet despite losing four of their past five to waste a 3-0 start. Those four losses are by a total of 10 points, so it's not as if they are being demolished.
And it would be a mistake, coach Marty Schottenheimer has said, to think they will greet the Chargers with anything less than their best effort.
It's a sink-or-swim game for the Bengals. For the Chargers, it's a fish-or-cut-bait.
Either you among the top-of-the-heap teams in AFC's, or you're not.
"It's going to be a test for us, no question," said LaDainian Tomlinson, who's being mentioned as an MVP candidate. "It's going to be tough going into their place. They're going to be ready. We have to match their intensity and be ready to go from the jumpstart. They're going to try to jump on us fast and get the crowd behind 'em."
If the Chargers can bolt from the gate, that Paul Brown Stadium crowd could quickly turn on the Bengals.
It should be loud either way.
It's up for to the Chargers to determine where the voices are directed.
The Bengals can't catch a break.
Reeling with four losses in the past five games, the Bengals will play host to red-hot San Diego on Sunday at Paul Brown Stadium. It's as close as a must-win game that can be played in the ninth outing of the season.
The Chargers are 6-2 and pose a terrible matchup for the Bengals. They run the ball well. The Bengals aren't good at stopping it. The Bengals have struggled offensively to move the ball and score points. San Diego's defense is stingy with points (sixth in scoring defense) and even stingier with yards (third).
At 4-4, the Bengals limped to the season's midpoint a far different team than many fans expected.
On Monday, the day after the Bengals dropped to .500 and two games behind Baltimore in the AFC North division, Marvin Lewis spent the early minutes of his news conference discussing his star wide receiver's verbal blowup, his team's apparent loss of composure and his quarterback's problems with his throwing motion.
The new season opened like it would meet all of fans' lofty expectations. The Bengals defeated a good Kansas City team on the road and then discarded rivals Cleveland Pittsburgh. Carson Palmer was back throwing the ball all over the field, just eight months after undergoing reconstructive knee surgery.
The defense was taking the ball away from the other team, and the offense was turning the gifts into points.
But 2006 has not unfolded as magically as 2005, when just about everything went right for the Bengals. Much has gone wrong so far.
The Bengals have a significantly more difficult schedule this season. The competition is better. Five of the Bengals' remaining eight games are against teams that are either in first place or share first place in their divisions.
Injuries have prevented the offense from reaching the stride that made it one of the NFL's most feared. After eight games in 2005 the offense had missed just one starter game because of injury.
This year, third-down back Chris Perry missed the first six games. Center Rich Braham has been out since Week 2. Left tackle Levi Jones has missed the last three games. No. 3 wide receiver Chris Henry was suspended for two games.
And Palmer has not been right. He said Sunday that his throwing mechanics have been affected by the knee injury. Palmer is not striding out far enough on the left leg, and, as a result, many of his throws are sailing high. He has been sacked 23 times in eight games, compared to 21 in all of 2005.
On Wednesday, the 10-month anniversary of the now infamous hit laid on Palmer's left knee by Kimo von Oelhoffen the quarterback discussed his ongoing efforts to return to the form of 2005 that made him look like a future hall-of-fame player.
"Last year, I felt when I was on the field I was just playing and reacting," Palmer said of the magical season in which he had 32 touchdown passes and an A-plus passer rating of 101.1. "I had been working so hard for the previous 20 years. When you go back and have to start all over, which is essentially what I had to do -- from laying in bed for three weeks and then being on crutches for six weeks to slowly being able to do bag drills, to be able to jog, to be able to run a little bit harder, to be able to sprint, to be able to jump and do all things -- you rebuild your mechanics from the ground up. It's something I'm continuing to do."
Palmer's still having a solid year. But he doesn't move around as well in the pocket as he did. Palmer also has not been nearly as consistently accurate. Palmer's 61.2 percent completion rate is 16th in the NFL, though his overall passer rating of 89.3 is ninth.
But Palmer's play is not the only reason the Bengals are 4-4 this year, compared to 6-2 a season ago, and is in danger of not repeating as a playoff team. The offensive line has struggled, in part, because of injuries and has not always given Palmer time to throw.
"Our quarterback is a lot better than he was two years ago," Lewis said. "Not quite as efficient as he was a year ago. We've allowed more pressure on the quarterback, whether it (is) the quarterback, the receivers (or) the backs, the line."
The defense and special teams, which had 28 takeaways at mid-season 2005, have just 14 now and not provided the offense with short fields.
"I don't think it has to do with Carson as much as it has to do with everyone," wide receiver T.J. Houshmandzadeh said of the team's losing skid. "Again, ya'll give the quarterback way too much credit when things go good. When things go bad, everybody wants to look at the quarterback. It's everybody. Carson's nothing without the o-line. We're nothing without him. He's nothing without us. Everybody has to be on the same page."