Yes, the Super Bowl also is the Super Bowl of advertising. And commercials are supposed to be part of the show, not an interruption. But there’s a discordant note amid the hoopla for Sunday’s match between the New England Patriots and Seattle Seahawks: Some experts suspect that advertiser interest in the game and network pricing either has peaked or soon will.

superbowl-xlix_home_page“Demand is clearly down for Super Bowl spots,” says Tim Calkins, a marketing professor at Northwestern University’s Kellogg School of Management who tracks the game’s ads. “The Super Bowl is important. But a lot of brands are saying that there are other things that they can do” to boost sales.

If he’s right, then it could be a big problem for broadcasters. Last year’s record-breaking Super Bowl accounted for about 7% of Fox’s total C3 ratings points for the TV season and, it reported, about $350 million in revenue.

Related ‘Jurassic World’, ‘Terminator: Genisys’ & ‘Tomorrowland’ Among Super Bowl Ad Spots

NBC might exceed that — but it was a struggle. The Peacock network asked for $4.5 million for a 30-second spot, 7% more than Fox commanded last year. Yet it faced “a challenging ad sales marketplace, I won’t diminish that,” says News and Sports Group EVP Seth Winter. “This hasn’t been the easiest exercise I have been through.” Indeed, it took until yesterday before NBC could announce that it had sold out its inventory of ads in the game. Last year, Fox did so two months in advance.

Several auto makers are expected to sit on the Super Bowl sidelines this year including General Motors, Ford, Honda, Infiniti, Jaguar-Land Rover, Mazda and Volkswagen. Meanwhile, Coca-Cola, Anheuser-Busch InBev and GoDaddy reportedly bought less time than they did last year.

Super Bowl XLVIII - Seattle Seahawks v Denver BroncosThat seems consistent with a broad storyline about TV’s anemic ad market. Buyers see declining ratings and increasing ad-skipping on DVRs and less-costly opportunities to reach potential buyers via digital media.

The Super Bowl is supposed to be the immune from those contagions. It’s a spectacle that nearly half of the country watches live. “There’s nothing even remotely close to the Super Bowl in audience delivery,” says Horizon Media SVP Research Brad Adgate. “It’s the last mass-media event.”

But the rising costs have also made the Super Bowl super risky for buyers. The price of airtime is “just the down payment,” says Kantar Media Chief Research Officer Jon Swallen. To justify the outlay, most companies need to spend heavily to produce a slick ad. Then they need elaborate PR and social media campaigns to make sure the bump in awareness lasts more than a day. This year lots of advertisers including Victoria’s Secret and Snickers began hyping their ads and even posting them on YouTube weeks ahead of the game.

Super Bowl ad clutterCompanies have to shout louder than ever to be heard as broadcasters pack the Super Bowl with ads and promotions. Last year’s match included 49:15 (that’s minutes:seconds) –nine more minutes than viewers saw in 2005 — Kantar Media reports. That would have been a new high if CBS hadn’t decided in 2013 to re-run a commercial pod to fill time when the lights went out during the game, lifting the total to 51:40. If you take that out and just look at paid ads, not network and NFL promotions, then last year set a record with 41 minutes.

RadioShack’s experience last year also demonstrated that even well-liked ads can fail to deliver a sufficient return on investment. The electronics chain used the Super Bowl to help modernize its image — and shuck the impression of it as an anachronism, where hobbyists go to buy soldering irons, transistors and capacitors. It poked fun at itself with a spot that featured Hulk Hogan, Mary Lou Retton, ALF and others titled “The ’80s Called: They Want Their Store Back.”

The bold marketing ploy did its job; RadioShack shares rose 7% the morning after it aired. Yet one year later, the stock is down 87%. “There’s all this hype, and by Tuesday it’ll be gone,” Swallen says.

That can be a blessing for ads that fail to impress viewers. In addition to scoring poorly on established rankings such as USA Today’s Ad Meter, creative failures risk being savaged on social media. “Nobody gets in trouble for running an ad on CSI: Miami,” Swallen says. “But they do if it’s the Super Bowl.”

With all of these complications, Calkins believes that Super Bowl ad pricing is at “a bit of a peak.” Next year, he forecasts, “they’ll keep the price flat.”

We’ll see. For now, NBC Sports Group Chairman Mark Lazarus says that Sunday will be “the biggest day for ad revenue in television history. … Our advertising sales have been vibrant. The business of football and the business of the Super Bowl is very good.” He wants the Patriots-Seahawks game to be “the biggest thing ever viewed,” with a measured audience of more than 125 million.

Adgate believes network and advertiser passion for the championship game will continue to grow: “There’s a subliminal connection it makes to consumers. It says, ‘We’re a blue-chip company, and we can afford this.'”

Perhaps just as important, execs understand that it can be risky to stay out of the Super Bowl if a competitor is prepared to jump in. Coke and Pepsi continue to buy even though “they receive no profit gain to offset their advertising investments,” says Wesley Hartmann of the Stanford Graduate School of Business — who just co-wrote a study of Super Bowl ads with Daniel Klapper of Humboldt University in Berlin. The beverage companies can see that Budweiser, as the game’s exclusive national beer advertiser, records a $96 million bump in sales.

If networks become too greedy with their ad demands, then it might hurt some of the shows around the event. But Swallen says there still are plenty of advertisers salivating to be part of the big game. “Eventually there’s a straw that breaks the camel’s back,” he says. “That straw isn’t there yet for the Super Bowl.”