It was a particularly happy Thanksgiving last year for the sales team at Fox Sports, and not because they were broadcasting a game between the Green Bay Packers and a Detroit Lions team that, shockingly, had not yet been mathematically eliminated from the playoffs. The reason for the corporate joy: More than two months before Super Bowl XLII, all but two of Fox’s 63 in-game commercial slots had been sold, and for record rates. This was a dramatic improvement from the previous few Super Bowl broadcasts, when networks were peddling their discounted inventory right up to the moment the big game's performer du jour was carted out to butcher the national anthem.

You’ve probably heard the ad numbers for this year’s game: Brands are spending up to $2.7 million for a 30-second spot on the February 3 broadcast, tossing at least $150 million into the pockets of Rupert Murdoch and the National Football League. According to Lou D’Ermilio, senior vice president of media relations at Fox Sports, selling out a Super Bowl at unprecedented prices while leaves were still on the trees in Manhattan was, well, unprecedented. Even taking global warming into account, this autumnal windfall has to be good news for big-time, big-brand, TV-heavy advertising, right?

It is, until you stop to wonder why. Why, this year in particular, were the megabrands so quick to commit to spending more money on 30 seconds of network airtime than it cost to produce most of the films being screened at Sundance? Advertisers sure aren’t splurging because of a robust economy, as they did in prewar, pre-Nipplegate, dotcom-infatuated 1999. No, they are going for broke this year because they’re desperate.

At first glance, that doesn’t make sense. After all, this is advertising’s biggest day of the year, and with the generous cooperation of the matchup gods, it may be its biggest day ever. What’s so desperate about that? What’s not to like about 93 million captive viewers, a third of them women, in more than 63 percent of American homes—all of them not just watching the ads, but anticipating, embracing (to the tune of 99.6 percent audience commercial retention—i.e., those who stick around for the whole thing), and critiquing them?

But take a look at what’s happening in Ad Land on the 364 days of the year that don’t feature an N.F.L. title game: Commercials are not discussed by consumers; they are treated with disgust—something to be zapped, TiVo’d, or DVR’d into oblivion. On those 364 days, many TV programs won’t be watched live; they’ll be watched whenever the viewer gets around to it, sometimes on a screen smaller than a Post-it.

On February 3, network TV could set a one-day viewership record, but on February 4—and on every subsequent day until next year’s game—viewership will revert to its ratings tailspin. Throw in a Writers Guild strike that has pretty much killed the new network season and it becomes glaringly obvious why brands with a big, timely story to tell gobbled up Super Bowl ad slots much earlier than usual this year. They had no choice.

“With the uncertainty in prime time, there’s definitely been a trend to advertise with live sports and megaevents,” says Tom McGovern, U.S. director of sports media for Optimum Sports, which buys ad time for Super Bowl perennial Pepsico. “Major brands need major outlets with mass reach to launch new products and campaigns. The Super Bowl is the best—and one of the last—places to make that kind of splash.”

Which explains why Cars.com, sister company of 2007 Super Bowl ad alum Careerbuilder.com and one of the few Super Bowl advertisers that hasn’t concealed its plans like a (pre-Valerie Plame) C.I.A. operative, is jumping on board for the first time this year with two 30-second ads. That buy is noteworthy to media and Wall Street types because the company’s brand name ends with “dot” and “com,” and it’s vital to Cars.com because a Super Bowl launch puts it in the year’s biggest show for its prime audience, auto dealers.

That large, captive audience is also why you will probably see more movie trailers this year than you’ve ever seen during a Super Bowl broadcast. Last year, there were four; this year, Fox has already booked 12. While trailers aren’t the kind of ads that will be passionately discussed in the blogosphere, they’ll be all over the game because of three letters: DVR. “If you’ve got a movie opening on a fixed date, you can’t wait seven days for people to look at your trailer,” says D’Ermilio at Fox Sports. “The Super Bowl is 100 percent DVR-proof.”

It is a popularly held belief that the Super Bowl ads of a given year reflect the zeitgeist of the day. This claim is generally supported with the usual suspects: Budweiser’s lizards (1997) taking the piss out of the concept of corporate spokespeople (the frogs) by trying to kill them; or Apple’s Orwellian, Ridley Scott-directed classic “1984” (1984); or the series of White House Office of National Drug Control spots (2002) that linked smoking marijuana to, among other things, terrorism.