Fox and CBS were the standout networks in the about-to-conclude television season, one in which the broadcasters overall lost more ground to cable.

Fox, riding the “American Idol” locomotive, made it five straight seasons as the top network in adults 18-49, with an average 3.6 rating/10 share, while also leading in all younger categories. CBS, meanwhile, placed second in 18-49 (3.1/8) and tied Fox for the adults 25-54 lead (4.1/10), according to Nielsen.

CBS also won in total viewers (11.8 million) for the sixth time in seven seasons, with its “The Mentalist” emerging as the most popular new show.

Third-place ABC (2.9/8) was propped up by its vets but got little help from its newbies. Alphabet edged out NBC, which finished fourth (2.8/8) in 18-49 for a fifth straight year despite airing the Super Bowl.

It was a rough year overall for the broadcasters, who were unable to fully recover in the first season since the writers’ strike.

Though they outperformed their averages from the strike-ravaged February, March and April of 2008, the major nets were down about 10% in each of the season’s other months. According to projections based on Nielsen “most current” averages through Sunday, the Big Four will finish down 5% in 18-49 and in the 2%-4% range in categories like 25-54 and total viewers.

While these declines are not bad compared to recent seasons, they’re a bit disappointing given that last year featured so many more repeats due to the strike-dictated work stoppage.

Ad-supported cable commanded 48.2% of the primetime 18-49 audience, according to Nielsen, up from 46.6% a season ago. The Big Four broadcasters, on the other hand, dipped to 29.9% from 31.6% in the 2007-08 season.

DVRs continue to change the way Americans watch primetime, with U.S. penetration hitting 31% in May (up from 25% in May 2008); it’s even higher among adults 18-49 (37%, up from 28% last year).

While some shows, including older-skewing faves like “CSI,” “Dancing With the Stars” and “NCIS,” still derive 85% or more of their audience from live viewing, many younger-skewing skeins are increasingly being recorded and played back on viewers’ own timetables. For the first time, a handful of shows this season (“The Office,” “Heroes,” “90210”) derived more than 30% of their audience from DVR playback, according to Nielsen’s “live plus 7” yardstick measuring DVR viewing done within seven days of the initial telecast.

Fox’s “American Idol” claimed the top two spots in the program rankings in adults 18-49 for a record six consecutive seasons. In total viewers it’s been No. 1 for four straight seasons. And despite declines of roughly 10% year to year, the music megahit actually opened up more ground on the rest of primetime.

That’s because the other highest-rated returning series all saw bigger declines, starting with ABC’s “Desperate Housewives” and “Grey’s Anatomy,” which were the top scripted performers in 18-49.

Rounding out the top 10 in 18-49 were NBC’s “Sunday Night Football,” Fox’s “House,” CBS’ “CSI” and “Two and a Half Men” and ABC’s “Lost” and “Dancing With the Stars.”

“CSI,” despite some noticeable declines in the months following William Petersen’s exit, finished the season as TV’s top scripted skein in both adults 25-54 and total viewers.

Other Fox highlights included “Fringe” emerging as the season’s top-rated new program in 18-49; “House” standing as the No. 1 8 o’clock scripted program in 18-49; rookie drama “Lie to Me” winning its Wednesday hour; and the combo of “Cops” and “America’s Most Wanted” leading Saturday for an 11th straight season.

Net also has reason to be pleased about the performance of the much-traveled “Bones,” which ranked No. 2 in its new Thursday 8 p.m. slot in 18-49 and No. 1 in 18-34.

CBS was the only network to post year-to-year gains in adults 18-49, adults 25-54 and total viewers, and it ranked No. 1 in women 25-54.

Highlights include “The Mentalist,” which matched its potent “NCIS” lead-in on Tuesday and was the season’s top newbie in adults 25-54 and total viewers. Also, the net possessed TV’s top-rated comedy block, led by “Two and a Half Men” — again the season’s No. 1 laffer — and a growth spurt for sophomore sitcom “The Big Bang Theory.”

The Eye was the top-rated network in the 10:30 p.m. half-hour leading into the late local newscasts, getting winning perfs from “CSI: Miami,” “CSI: NY” and “Numbers.”

ABC struggled early in the season but came on late, with its 2009 performance slightly ahead of its 2008 showing. Alphabet finished on top among women 18-49 while tying NBC for second among adults 18-34.

“Grey’s Anatomy” finished as the biggest DVR gainer, rising from 15.2 million viewers in “live plus same day” averages to 17.6 million when all same-week playback is counted.

NBC had a few things worth boasting about, including strong numbers for “Biggest Loser” and improved ratings for “30 Rock,” but they weren’t enough to bring it out of the cellar. Its only top 10 show was “Sunday Night Football” at No. 3, although “The Office” and “Heroes” made the top 15.

The Peacock finished roughly flat vs. last year in 18-49 and total viewers while gaining a bit in adults 18-34. “The Office” finished as TV’s top-rated scripted program in 18-34.

Among the smaller networks, the CW topped MyNetwork in 18-49 (0.9/2 to 0.6/2), 18-34 (1.0/3 vs. 0.5/2) and total viewers (2 million to 1.7 million). MyNet took over the “WWE Friday Night Smackdown” franchise from CW, resulting in gains for MyNet and declines for CW.

CW’s top shows in its target 18-34 demo were “America’s Next Top Model” and the Monday tandem of “Gossip Girl” and “One Tree Hill.”

* * *

In the final full week of the season, Fox prevailed in 18-49 (3.3/10), but ABC and CBS (2.9/8) weren’t far behind. Fox edged CBS in adults 25-54 (3.9/10 to 3.8/10) while CBS won easily in total viewers (11.2 million to 9.4 million for runner-up ABC).

One week from the show’s season finale, Fox’s Wednesday “American Idol” results show spiked and was the frame’s No. 1 skein (8.7/22 in 18-49, 24.67m), outperforming Tuesday’s performance seg (8.0/23, 22.71m).

The Alphabet got a boost from the two-hour finales of “Grey’s Anatomy” (5.9/16 in 18-49, 16.53m), “Desperate Housewives” (4.7/12, 13.96m) and “Lost” (4.4/11, 9.43m), while the Eye benefited from Sunday’s finale of “Survivor” (4.2/11, 12.94m).

NBC had a strong showing Tuesday with the finale of “Biggest Loser” (4.7/13 in 18-49, 11.85m), which gave the net its best Tuesday (excluding the Olympics) in more than three years (Daily Variety, May 14).

The NBA Playoffs scored again, with Sunday’s Game 7 of the series between Orlando and Boston averaging 8.38 million — the most-watched second-round NBA playoff in cable history — and Thursday’s Game 6 between Houston and Los Angeles drew 7.35 million on ESPN.