Networks Compared to Previous Seasons
Using only original, non-sports series, NBC barely eked out the season title, 102.59 to 102.14 over CBS. It's NBC's first season win since the final season of Friends in 2003-04. It also means that all four members of the big four have won the season within the last five years.
I feel like I say this every year, and it's getting kinda tiresome, but it's worth a reminder that all these networks are historically close together. There's a tendency (like with journalists at the press tour) to treat the first-place network like geniuses and the fourth-place one like utter morons, but we're talking about a seven-point difference from top to bottom here. And nowadays, seven points in Plus is like a tenth of a ratings point. This was even more of a convergence than the last couple years, as NBC was the weakest first-place network in the era and ABC the strongest fourth-place. Clearly, nobody is even remotely on the dominance level of NBC during the Must See TV years, or Fox during the peak American Idol years. On the other hand, even if you think the league average is declining more than it should be, it'd be hard to argue any of these networks are in as bad a condition as NBC circa 2011.
Will 2016-17 bring any actual separation? It's hard to predict that since it depends heavily on the new shows. However, it should be noted that Fox's growth this season really came from three places: 1) a strong final season of American Idol; 2) an extremely successful revival of The X-Files; and 3) getting an additional six hours of Empire at the same giga-hit Plus level as season one. The first two of those will be off the sked completely. And it's very likely to be all downhill from here for Empire, because that's just the kind of show it is. So Fox could be a candidate to separate from the pack in a bad way.
Networks Across the Season
I looked at this in some detail at the beginning of March (week 23) so you can read that for more. As predicted then, Fox fell off from the pack a bit in the last three months. NBC picked up a couple points in the first two weeks after The Voice's return, but a somewhat disappointing ratings season for Voice made the momentum tough to sustain. So the networks were all pretty much flat from there.
One funny note here is that NBC actually fell behind CBS in the un-roundeds through the second half of week 35. It was only in those last three days, with NBC's Voice finale up against a bunch of filler from CBS, that NBC was able to pull back ahead. CBS nearly treated this 36-week season like it was a normal 35-week one, wrapping up pretty much all its heavy hitters (even Survivor) during the next-to-last week of May sweeps.
A Deeper Look at Networks
A notable milestone here is that NBC won the season in originals despite finishing fourth in scripted originals, which is a first for the A18-49+ era. That might seem hard to do, but we've been very close several times in the past; the closest was in 2005-06 during the rise of American Idol, when season champion Fox was just a point ahead of NBC in scripted. And NBC's been within three points of the lead with fourth-place scripted in the last couple years.
It's also worth noting that this was the eleventh straight season that NBC has been fourth in scripted. They had clawed to within a point of Fox in 2013-14, but Empire's arrival the next season shut the door.
In fairness, NBC has, despite its fourth-ness, made a solid amount of progress in scripted ratings of late. This 89 was its highest average since 2007-08, when Heroes, SVU and the The Office-led comedy Thursday were all still in their primes. NBC went as low as sixty-six, meaning its average scripted original was a "flop" by the full big four standard, in 2011-12.
ABC and CBS were each down a touch from their 70% original peaks last year, but NBC and Fox both rose to 63%. That was enough to take the overall big four original percentage to a new A18-49+ era high 66.4% (up from 65.7% last year).
Here's the now updated A18-49+ Networks post.
Here's the now updated A18-49+ Deeper Networks post.