By DAVE GOLDBERG

AP Football Writer

Just when the Indianapolis Colts seemed to be back in form, they weren’t, following up a 31-3 win over Baltimore with a 34-14 loss in Green Bay in which the only two touchdown passes Peyton Manning threw were to the Packers.

The San Diego Chargers? It was easy to figure they would falter in Buffalo, where they lost 23-14. Every time they’ve played well this season, they’ve followed with a bad game. So it figured to be tough against the Bills after the Chargers’ 30-10 prime-time win over New England a week ago.

The Colts and the Chargers, a combined 97-31 over the past four regular seasons, symbolize what’s been happening in the NFL this season. Like many well-regarded teams, they are stumbling and inconsistent. The Colts are 3-3 as they head to Tennessee (6-0) to try to keep alive their hopes of a sixth straight AFC South title; the Chargers are 3-4 as they go to London for the NFL’s European showcase against New Orleans.

“This is kind of the way we have been all year,” Tony Dungy said after the Colts’ debacle in Green Bay. “We have been up and down and not consistent. We showed more of that today. Green Bay played smarter and sharper than we did, and consequently won the game by a big score.”

Indy and San Diego, of course, aren’t alone among stumbling favorites.

The best example is Dallas (4-3), a consensus favorite to win the Super Bowl by those who disregarded the lack of chemistry that was obvious before the season began. The 34-14 loss to St. Louis was its third in four games and led to a locker room dressing down by owner/coach/wide receiver Jerry Jones, who might play quarterback himself next week unless he orders the injured Tony Romo back in the lineup.

You can add Minnesota (3-4), whose fans had their hopes unrealistically heightened by the offseason acquisition of pass rusher Jared Allen; New Orleans (3-4), which added some defensive parts and then got Jeremy Shockey for an already explosive offense; and Seattle (1-5), which had won five straight NFC West titles.

But Indy and San Diego are the best example of why it’s best not to predict any season based on past performance or offseason pickups.

Both have been hit by injuries, most often the reason teams fail to meet expectations. The absence of Bob Sanders and Shawne Merriman from their respective defenses has created major havoc with those units. And aside from that win over the Ravens, Manning seems to be at less than top form, perhaps the result of two preseason procedures to remove a bursa sac from his left knee.

On the other hand, maybe both teams are just slipping back into the back, especially the Colts, who are getting old at some positions.

Indy has always had problems on defense, especially against the run because it has let defenders go in order to pay big money to Manning and other offensive stars. In 2006, when it won the Super Bowl, it was last in the league in rushing defense for most of the season before the return of Sanders from injury added to trade-deadline acquisition of Anthony McFarland and shored up things dramatically in the playoffs.

But in that year and in others, the Colts’ ability to outscore opponents forced other teams to play catch-up and, late in the game, abandon the run.

In fact, in 2004, the last time they played the Packers before Sunday, Manning and Brett Favre engaged in a classic shootout, leading their teams to touchdowns on the first five possessions. The Colts eventually won 45-31, a not uncommon score during the Manning era.

Now Sanders is hurt; McFarland, injured again, is out of football; Dwight Freeney is still not 100 percent after a foot injury; Marvin Harrison is 36 and coming off a knee injury; and offensive left tackle Tarik Glenn has retired. Beyond that, the Colts are making uncharacteristic mistakes – they were called for 12 penalties for 110 yards in Green Bay and have had 23 in the last two weeks after having just 67 all of last season.

In any case, their run of division titles is almost surely over unless they can find a way to win at Tennessee next Monday night. And even if they do find a way to stop a 6-0 team that rushed for 332 yards in Kansas City on Sunday, the Colts don’t seem consistent enough to make a run at a team already three games ahead of them.

Plus, the Jaguars – yet another inconsistent bunch – could be a factor in the division.

That would make the Colts at best a wild-card contender. And if they stay around .500, they may have to bring back ex-coach Jim Mora to reprise his legendary “PLAYOFFS!! PLAYOFFS??” routine uttered after an ugly loss in 2001. No, the Colts didn’t make the playoffs that season.

The Chargers’ inconsistency again raises questions about Norv Turner, who for the last two decades has been more successful as an offensive coordinator than a head coach. He was in Washington and Oakland before taking over the Chargers when Marty Schottenheimer was fired after a 14-2 record in 2006.

But it goes beyond that and the injuries to Merriman; to his backup, Jyles Tucker; to Chris Chambers, the wide receiver who made so big a difference after he was acquired last season from Miami; and to LaDainian Tomlinson, who has been playing with a sore toe that makes it hard for him to cut.

True, the Chargers started 2-3 last season before finishing the season 11-5 and going to the AFC title game, where they lost to New England. But that was in a weak division where the second-best team, Denver, finished 7-9.

This year, the Broncos are better. That leaves the Chargers, who lost in Denver in part because of referee Ed Hochuli’s mistake at the end of the game, less room for error.

They’re also not playing well enough to make anyone think a winning streak is in the works. The power outage in Buffalo wasn’t only in the stadium, it also was in the Chargers’ offense.

Philip Rivers was 22-of-29 for 208 yards and threw for two touchdowns. But he also turned the ball over twice, including a late interception by Kawika Mitchell that killed a drive for a go-ahead score after the Chargers had moved to the Bills 9. That’s just more of the inconsistency that has plagued San Diego all season.

“At some point, if we want to be the team that we believe we can be, we have to start playing that way,” defensive tackle Luis Castillo said.

Saying that is one thing. The way the Colts and Chargers are going, they simply may not be as good as they believe they are.

Or that other people believed they were.