After a busy weekend in which it locked in a handful of its remaining Super Bowl spots, Fox's ad sales team heads into the home stretch with just two or three in-game units left to move.

"We are first-and-goal on the one yard line," Fox Networks Group exec-VP, ad sales Bruce Lefkowitz said this afternoon. "We're not ready to line up in the victory formation just yet, but we're confident that when we're done, Sunday will be the highest-grossing day on record for Fox, and we'll certainly have secured the highest rate for a Super Bowl spot."

Fox is charging advertisers about $5 million for each 30-second slice of its Super Bowl LI in-game inventory, and while much has been made over the fact that the network still has units to sell at this late date, this is hardly an unprecedented state of affairs. Just two days before Super Bowl 50 kicked off, CBS still had a few spots held back for last-minute shoppers, and the year before that, NBC closed out the last of its deals just a few days before the big game.

Until very recently, the NFL's broadcast partners liked to make a show of proclaiming that they'd shifted the last of their in-game units as early as the preceding December, or before the playoffs got underway. Of course, the Super Bowl may only be said to be truly sold out after the first elated victor takes to the turf to make the first confetti snow angel; not only do the networks always keep a couple available spots on ice in the interest of exploiting zero-hour overtures and impulse buys, but come hell or high water, they'll figure out a way to carve out an extra half-minute of airtime if the price is right.

Media buyers said that Fox may have had a few additional units at its disposal because it had reserved a bit of time in the hopes that a Cowboys-Patriots or Packers-Patriots matchup would drive up pricing. When both scenarios failed to materialize -- the underexposed Atlanta Falcons will square up against the Pats in Houston this Sunday -- any prospect of commanding a premium for the remaining units deflated like a football in a Gillette Stadium restroom.

If latecomers were discouraged by the lack of a hypothetical dream matchup, the market also has been impacted by a generalized malaise that can perhaps be best characterized as "the jitters." While Super Bowl LI promises to deliver the biggest TV audience of the year, marketers understand that with massive exposure comes the risk of spectacular creative failure.

"In recent years, the USA Today ad tracker and social media have played a greater role in the sale of the Super Bowl than many other factors," Mr. Lefkowitz said. "The fact is, a Super Bowl commitment far exceeds the actual unit price. No one wants to see that their creative ranked at the bottom of the ad tracker -- even if there is no correlation between that score and brand lift or a subsequent increase in sales."

Putting your message out in front of 110 million-plus consumers is not for the faint of heart, and if you're the CMO who signs off on a spot like Nationwide's notorious "Dead Kid" ad of two years back, you're going to find yourself out of a job. (Certainly not helping matters in that particular instance was the fact that one of the agents of the boy's demise was a television set, for crying out loud -- this, while a nation huddles around the tube to celebrate our great secular holiday.)

The Nationwide blunder is an extreme example of how advertisers' understandable aversion to being scrutinized by an ever-expanding corps of Monday morning quarterbacks continues to keep network sales execs on their toes. "Super Bowl creative is like a fickle friend. If somebody loves their creative, a 30-second spot turns into a :60. If they hate it, five spots can turn into zero. It happens, "Mr. Lefkowitz said. "And that's why you have to wait until the final gun sounds, when the clock hits zero."

Mr. Lefkowitz said that a number of interested parties are circling around the last remaining spots, before adding that the units could be off the books for good by mid-week.

Super Bowl ratings? Meaningless.

On the heels of one of the lousiest, least competitive NFL postseason runs in memory, Fox heads into Super Bowl LI facing something of a conundrum. After setting ratings records (fleeting as they may have been) in each of its last three Super Sunday broadcasts, can the network keep its streak alive with a matchup between one of football's most overexposed franchises and a team that hardly ever appears on national TV?

Short, qualified answer: It could happen, but the distinction is largely meaningless, given that Fox isn't beholden to hit any predetermined audience targets. As with fellow rights holders NBC and CBS, Fox doesn't offer ratings guarantees to its Super Bowl advertisers, so there's no danger of it being on the hook for makegoods. When it comes right down to it, Super Bowl ratings are primarily about bragging rights; as there's no longer a correlation between the final Nielsen tallies and the subsequent rate hikes, they're not even all that useful in establishing a baseline unit cost for the next network in line.

"At this point, you know you're getting a 46 [household rating] no matter what," said one national TV buyer. "A point here and there, a few million people one way or the other -- none of that matters when you're dealing with an audience that size."

If Fox hopes to top the established record set by NBC and Super Bowl XLIX, it will have to surpass an average draw of 114.4 million viewers.

Since 2010, when CBS's coverage of Super Bowl XLIV broke the 100 million-viewer mark for the first time, the big game has never been in any danger of slipping back into the high 90s. And while the absolute year-to-year gains have been proportionately modest, the rate of change on pricing is basically a hockey stick. In the last eight years, the going rate for a 30-second spot has jumped nearly 80%, from $2.8 million a pop to in excess of $5 million, and the average CPM increased 63%. It took 10 years for the networks to raise the average unit cost from $2 million to $3 million, but the leap from $3 million to $5 million happened in just eight.

The good news for advertisers who will take the plunge with Fox this Sunday is that, barring a nuclear strike or a power outage that plunges the Northeast megalopolis into darkness, Super Bowl LI is going to put up the usual towering numbers, and their commercials will generate millions of impressions, both during the live broadcast and in the ensuing days and weeks. (As noted above, this can prove to be a decidedly mixed blessing.)

Déjà voodoo

Representing the NFC are the Atlanta Falcons, a high-flying, score-at-will squad which for years has been remanded to the NFL's version of the witness protection program, appearing in just two or three national TV windows each season, while drawing fewer viewers than an episode of the CBS procedural "Bull." Lining up on the other side of the ball is a grimly efficient New England Patriots team that, for those of us who don't reflexively employ the word "wicked" as an all-purpose adverbial modifier, is about as wearisome and implacable as the specter of death.

(Incidentally, this sort of braying provincialism isn't going to make the rest of us any less enthused about the prospect of yet another Patriots Super Bowl victory.)

For casual fans, this is the ultimate battle between Matt Who? and Ugh, Him Again. Suiting up for his seventh Super Bowl is the G.O.A.T., Tom Brady, with his four rings and his matinée idol looks and his multiple endorsement deals and his giant stupid coat. Face it: Unless you're Bill Simmons or a Wahlberg, you're sick to death of this guy. On the other hand, there's Matt Ryan, a man with two first names who shills for Dannon yogurt and was once considered such a choke artist that his likeness may as well have been superimposed on the Heimlich maneuver posters in all downtown Atlanta restaurants.

While New England enjoyed significantly more TV exposure during the regular season -- the Pats were the NFL's No. 4 most-watched franchise, averaging 20.5 million viewers in their six national appearances, while the Falcons ranked 23rd with an average draw of 12.2 million viewers in three coast-to-coast games -- the playoffs were a great equalizer. According to Nielsen live-plus-same-day data, Atlanta's two postseason broadcasts drew nearly as big of a crowd as New England's playoff games, as the birds averaged 37.5 million viewers to the Pats' 38.9 million.

As it happens, none of the cited Nielsen stats amounts to a hill of Boston baked beans. There is no correlation between regular season/playoff ratings and Super Bowl deliveries; in fact, the decade's second lowest-rated Championship Sundays led directly into the most-watched Super Bowl (the aforementioned 49th edition).

At which point, it's probably worth noting that this Super Bowl will likely be a refutation of last year's stultifying defensive scrum, which featured a Panthers squad that racked up more turnovers than third-down conversions and a past-his-sell-by-date Peyton Manning amassing a pitiful 56.6 quarterback rating. The over-under for Sunday's game is a dizzying 59 points, the highest ever for a Super Bowl, and a reliable indication that the oracles of the Mojave Desert believe that Brady and Ryan will put on a real airshow at NRG Stadium. New England is a 3-point favorite, and despite the fact that 63% of the spread cash is landing on the Pats, the line has held fast. This has all the markings of a closely matched, high-scoring game. If the outcome is still in doubt at the two-minute warning, this one sets another record.

Call it Falcons 31, Pats 29, setting a new record by the merest dermal-dental layer with an average draw of 114.9 million viewers. Fox books north of $400 million in in-game revenue … and in a few weeks time, NBC makes it known that the going rate for a :30 in Super Bowl LII is $5.4 million.

Super Bowl LI kicks off Sunday, Feb. 5, at 6:30 p.m. EST on Fox.