Tom Brady and Shawne Merriman are lost for the season, a major blow to the Patriots and Chargers. Indianapolis looked ragged last week with a rusty Peyton Manning and a missing Jeff Saturday. Jacksonville’s offensive line is hurting.

Not a good start for some of the AFC’s powers. And maybe a shift in the balance from the AFC to the NFC, which won only its second Super Bowl in the last eight seasons and third in the last 11 when the Giants upset the Patriots last February.

It begins, of course, with injuries, something that affects both conferences. But even before the season started, they seemed to hit the AFC harder.

Brady, for example, didn’t play one down in exhibitions because of a foot problem that was never further explained, standard fare for Bill Belichick. In the 7 minutes he played against Kansas City, he looked less mobile than usual. Did that prevent him from avoiding the hit that knocked him out for the season? Probably not, but who knows – he was banged around in the Super Bowl by the Giants when he was playing with a sore ankle.

Manning had a bursa sac removed from his left knee just before the start of training camp, practiced just a week-and-a-half and didn’t look like himself against the Bears. Chicago’s active defense also exploited the absence of Saturday at center to crash the middle of the Colts’ offensive line.

Coaches are more stoic about those things than fans because they’re used to it. So they simply plug in the next guy and hope he can play.

“I think great teams overcome those types of things,” Indianapolis’ Tony Dungy said after Brady was injured. “Matter of fact, I remember it happening when Drew Bledsoe got hurt. There was a guy we didn’t know a whole, whole lot about and most people were predicting doom and gloom for the Patriots at that time. It ended up the guy they put in was pretty good.”

The guy they put in, of course, was named Brady.

It’s very unlikely Matt Cassel will reach that standard, although he could do well enough to get the Patriots to the playoffs with the talent around him. And while Jyles Tucker, who replaces Merriman, has played only seven NFL games, the Chargers, who know what they are doing, gave him a five-year contract extension even after so little exposure.

Merriman’s absence also gives Shaun Phillips, a similar type player previously known as “The Other Guy,” a chance to emerge from the shadows.

Good organizations, New England, San Diego and Indy among them, always draft with depth in mind and don’t worry about stacking good players at key positions. That doesn’t include Detroit, which used its first-round pick on wide receivers in four of five years with 50 percent success: Charles Rogers and Mike Williams were duds; Calvin Johnson and Roy Williams aren’t.

As for the balance of power, look at the first week: Chicago winning at Indianapolis and Carolina at San Diego. Plus Dallas’ 28-10 win in Cleveland, not an upset but a thorough thumping by an NFC power on the road against an AFC team that was supposed to contend.

Although it’s just one week, that may portend a shift that really began last season in Dallas, Green Bay and New York, but was overshadowed by New England’s dominance – until the Super Bowl.

The Patriots are still a good team without Brady, but certainly not as dominant as they were last year. The Chargers and Colts may slip a notch and Jacksonville, a popular sleeper pick for the Super Bowl, lost both starting guards for the season and were physically manhandled in their opener in Tennessee.

On the other hand, the NFC East alone has three teams with the potential to go deep into the playoffs. The Cowboys are a consensus Super Bowl favorite; the Eagles are solid as long as Donovan McNabb stays healthy; and the defending champions, even without Strahan and Umenyiora, are not the fluke a lot of people thought they were.

New Orleans, Carolina and Tampa Bay make the South pretty formidable. Minnesota, Chicago and Green Bay look decent in the North, leaving only the West barren: Seattle is banged up and Arizona is historically challenged.

Look at the most important position: quarterback. With Brady out, the NFC may have more good ones – or at least as many.

Think McNabb, Tony Romo, Eli Manning, Drew Brees. Think Matt Hasselbeck, although he has no receivers these days, and Marc Bulger, who has little support on a bad team in St. Louis. Plus Aaron Rodgers in Green Bay, who isn’t the next Brett Favre but is certainly better than Alex Smith, who went No. 1 overall in the 2005 draft, when Rodgers went 24th.

And, of course, Jake Delhomme, in whose absence Carolina slipped to 7-9 last season. He’s back from elbow surgery and beat San Diego last week on a last-play TD pass.

The AFC?

Favre is there now, if only for a year. Ben Roethlisberger is among the league’s top QBs and while Carson Palmer had a bad opener, most teams would grab him in a minute.

Big brother Peyton will shake off the rust; Jacksonville’s David Garrard is too often overlooked; and Jay Cutler, the diabetes that plagued his 2007 season diagnosed and under control, could have a big year in Denver.

But good QBs now seem relatively balanced between the conferences.

Last year, the AFC and NFC split 32-32, although that’s an overrated stat because it doesn’t take into account the fact that an AFC strong at the top had dogs such as Oakland, Miami and Kansas City at the bottom to get beaten up by average NFC teams.

In any case, the NFL is always in flux.

Go back 15-20 years, before the era of TV and Internet jibber-jabber by uncredentialed “experts,” to one of the overlooked wise men in NFL history. That’s the late George Young, who took over the Giants in 1979, built them into a Super Bowl team and influenced many of the men who today are among the game’s wisest – from Bill Parcells and Bill Belichick to Indianapolis’ Bill Polian, who acknowledges Young as one of his mentors.

Sometime in the early 1990s, when the NFC was in the midst of winning 13 straight Super Bowls, Young was asked if the AFC would ever come back.

“Come back?” he asked in the faux-gruff tone he always used. “It never went anywhere. It’s cyclical. Everything is cyclical.”

The AFC came back. Now it may be the NFC’s turn again.