We're at the midway point of the 2016-17 broadcast TV campaign, and the network suits all have one eye trained on how their current schedules are faring and the other on pilot season and the year ahead. And while the ongoing decline in live viewing is having a demonstrable impact on commercial deliveries, thereby further complicating the assessment of the shows that are on the bubble, the rare hits are easy to spot.

If last season was marred by the absence of a breakout success, this year has given rise to at least one unambiguous new smash. With an average C3 score of a 3.1 among adults 18 to 49, NBC's multigenerational drama "This Is Us" stands as broadcast's second highest-rated drama and the No. 3 scripted show. NBC is so chuffed with how Dan Fogelman's emo epic has connected with fans that on Wednesday it announced it had renewed the show for not one, but two, additional seasons.

NBC doesn't own "This Is Us," which is produced by 20th Century Fox TV, but it certainly generates a nice chunk of ad revenue for the Peacock. NBC was so certain that "This Is Us" would prove to be a hit that during the summer upfront interval, its sales team charged advertisers a premium for time in the show. Buyers last fall reported that they shelled out north of $250,000 for each 30-second spot, making "This Is Us" NBC's priciest scripted program. If precedent holds, sponsors looking for time in season two can expect to fork over at least another $100,000 on top of that already elevated rate.

Of course, for every "This Is Us" there are a dozen overpriced, underperforming shows that have about as much of a shot at making a comeback as vaudeville. TV is a binary system, and this season particularly reflects that on/off, ones-and-zeroes dynamic. What follows is a snapshot of the top 25 broadcast shows (through Week 17) and a look at some of the trends that are shaping the marketplace.

Your favorite shows are either old enough to vote or still in diapers.

Ten of the series in the top 25 have been on the air for at least 10 cycles, and two have been around so long that they're practically Methuselahs. Launched in 1968, if CBS's "60 Minutes" were a person, it would be on the verge of aging out of the 18-to-49 demo. In the midst of its 28th season on Fox, "The Simpsons" is America's longest-running scripted TV show, while the age-defying "NCIS" (14 seasons) and "Grey's Anatomy" (lucky 13) are the top-rated dramas at their respective parent networks. "Survivor," the show that helped power CBS's dominance over the broadcast pack, heads into its 34th cycle this spring, and ABC's "Dancing with the Stars" in March will suit up for its 24th spin around the parquet.

On the other side of the age continuum are the seven freshmen scripted series that have broken out this season, a roster that includes some familiar faces -- CBS's "Kevin Can Wait" stars "King of Queens" linchpin Kevin James, and "Bull" features "NCIS" vet Michael Weatherly -- as well as some relative unknowns like "Star" chanteuse Jude Demorest and Micah Fowler, who plays J.J. on ABC's "Speechless."

The influx of new shows in the top 25 suggests that viewers are still willing to sample fresh product, especially when the newbies are placed in protected time slots, where the lead-ins are generous and the competition isn't as formidable. Of course, a show that thrives in a prime position can just as easily wither when evicted from that slot; each of the four freshman shows ("Blindspot," "Life in Pieces," "Chicago Med," "Supergirl") that were in the top 25 at the midway point of the 2015-16 season were bounced from their cozy nests -- "Supergirl" was shifted to an entirely different network -- and their ratings have suffered for it. For example, since NBC uprooted "Blindspot" from its plum Monday 10 p.m. cubby and placed it in its Wednesday night anchor hour, the procedural's demo ratings have plunged 36%.

Some of the most expensive shows for advertisers are hemorrhaging viewers.

The TV market is governed by the hoary principles of supply and demand, and while upfront pricing generally errs on the side of promising a bit more than you may actually deliver -- it's better to overstate a show's value and dole out makegoods than low-ball it and leave money on the table -- for the most part, sellers tend to have a finely-calibrated sense of how their schedule will perform. Naturally, there are exceptions. While Fox knocked about 12% off its asking price for season three of "Empire" (a 30-second spot purchased in the upfront fetched around $437,000), the show's ratings are down 33% compared to the year-ago period. ABC shaved about 12% off the going rate for "Quantico," which has gone on to lose 47% of the in-demo audience that it reached in its first season. And NBC jacked up the rates for its veteran procedural "Law & Order: SVU" by a good 30%, only to see the show's ratings slide 7%.

On the other side of the ledger, "Grey's Anatomy" continues to earn its keep as the priciest draw in the ABC lineup, while two of the biggest bargains in primetime are CBS's Friday night dramas "Hawaii Five-0" and "Blue Bloods." While both shows may skew older, they're also a steal, with their average unit costs at about a 35% discount to competitors like "Shark Tank" and "Emerald City." You may not want to lean heavily on Steve McGarrett and the Reagan clan if you're looking to move bubblegum and Apple Watches, but if you're in insurance, pharma or retail and trying to interface with the upper reaches of the 25-to-54 set, CBS's weekend procedurals should not be overlooked.

Live viewing continues to evaporate, and C3 isn't doing much to win back lost commercial deliveries.

Season-to-date, the Big Four networks have seen their average draw of adults 18 to 49 fall 7% compared to the year-ago period, and the supply of adults 25 to 54 has shrunk 5%. With an average primetime rating of a 2.7 among adults 18 to 49, NBC is the most stable broadcaster, showing no change versus the midway point of last season and ticking up 4% compared to this time two years ago.

Bolstered by its mammoth World Series ratings, Fox is also steady (2.0) versus last season and is within a tenth of a point of its midseason form in 2015. The other two biggies are in a much tougher spot, however, as CBS is currently down 16% in its target demo (adults 25 to 54) and off nearly a full quarter (24%) versus two years ago, while ABC's 18-to-49 deliveries have dropped 11% to a fourth-place 1.7. That marks a 19% decline from a 2.1 in January 2015.

Strip out sports and news (content that also happens to deliver a disproportionate number of live viewers) and there isn't a network that comes within arm's length of a 2.0 rating. In terms of general entertainment programming, NBC maintains a slim lead over the field with an average draw of a 1.8, a few ticks north of CBS (1.6), ABC (1.6) and Fox (1.5). Per Nielsen, sports and news account for 33% of NBC's overall primetime deliveries and 25% of Fox's numbers. CBS (16%) and ABC (8%) are less dependent on live programming, which in the past few seasons has put both networks at a distinct disadvantage to NBC and Fox.

If sports have helped NBC and Fox retain a certain level of equilibrium, the general downturn in scripted ratings are plain to see on a show-by-show basis. Of the 75 returning series that have aired since the season began back in September, only two ("Hawaii Five-0" and "Bob's Burgers") have exhibited year-over-year ratings growth. The average rating among adults 18-to-49 for a scripted broadcast show is now a measly 1.2; at this juncture in the 2015-16 season, it was a 1.4. And as the numbers keep shrinking, it's getting harder to figure out where rock bottom is. This season, 34 shows are averaging less than a 1.0 in the demo, up from 22 a year ago. Not so long ago, a 3.0 was the Mendoza Line that separated success from failure; today, only five primetime broadcast shows draw north of that mark in live-same-day ratings -- and three of them are NFL packages.

None of this would be so difficult to process if the millions upon millions of time-shifted deliveries somehow factored into the ratings calculus, but as we have demonstrated so many times before, viewers who play catchup don't watch the ads. All the DVR deliveries in the world won't help a show hit its guarantees when those delayed views don't show up in the currency data. At last count, the average lift from live-same-day to C3 was just two-tenths of a ratings point -- or a little better than a rounding error.