Analysis: DVR viewing giving fall TV shows a critical ratings boost TV executives used to look at DVRs as assassins that could kill their business. But this fall, the recording devices are seen as saviors. Two weeks into the new season, none of the fall shows has broken through the clutter and looks poised to become a smash yet, although NBC's post-apocalypse drama "Revolution" and CBS' Sherlock Holmes update "Elementary" have shown promise. Many returning shows - including ABC's "Dancing With the Stars" and Fox's "The X Factor" - have posted lackluster numbers. On Wednesday night, ABC's new country-music soap "Nashville" opened to unspectacular results, while "Chicago Fire" failed to heat up the ratings for NBC. Full coverage: Television reviews But network bosses aren't panicking over the mediocre results yet, because they say that in these days of fragmented media and shortened attention spans, it takes a long time to figure out what's working. Americans' DVR queues may resemble the debris-filled domiciles on "Hoarding: Buried Alive." But if fickle viewers finally do get around to watching the shows within three days of the original airing, the viewership totals as measured by Nielsen can jump by 25% or more. That can mean the difference between cancellation and survival. "Nothing has broken out and is looking like a massive hit," Dan Harrison, executive vice president for Fox Broadcasting, said of the new fall shows. But it's still too soon to tell, he added, because the traditional practice of making programming decisions based on ratings the morning after a show airs no longer makes sense. REPORT: Fall TV preview "Next-morning ratings are increasingly problematic," he said. It can take Nielsen days or even weeks to tally up complete numbers these days for a single show. Just looking at it the next day captures a small part of the picture. That's due to the effect of DVRs, which have finally reached critical mass in American households. The devices were first introduced in 1999. Six years ago, just 1% of households owned a DVR, according to Nielsen. As of last month, more than 45% did. Executives worried for years - and still do - that DVRs' ability to skip ads can lower prices for commercial time, the sale of which enables broadcast networks to pay the bills. But the devices are also having a halo effect on ratings, especially for scripted comedies and dramas. Increasingly, viewers use their flat-screens to watch, say, NFL games or the Emmys in real time and then stash everything else on their DVRs to watch later at their convenience. VIDEO: Fall lineup trailers Network bosses have created a euphemism for the latter, calling it "DVR lift." "The 'appointment-viewing' thing has all gone away, except for live events and sports," said Christine Chen, director of communication strategy at ad agency Goodby, Silverstein & Partners in San Francisco. NBC's "Revolution" is a case in point. Last month's premiere drew 9.2 million total viewers - a respectable if unexciting figure. But once viewers who watched over the next three days were thrown in, the total leaped 40% to 12.9 million. To NBC executives, that sounds like a hit. "'Revolution' is a real number, especially if you look at the DVR numbers," said Jeff Bader, the longtime scheduling chief NBC recently hired away from ABC. But trying to decipher those ratings can befuddle even the professionals. Executives have to sift through Nielsen numbers that count viewers on the night a program airs as well as viewing within three days and within a week. Other figures, designed to overcome advertisers' objections about ad-skipping, estimate how many viewers watched the entire program without fast-forwarding through commercials. And more data may be on the way: Executives say they still lack reliable intelligence on how many watch digital services such as Netflix. "On any given day, we're now getting five data sets released to us," said CBS scheduling guru Kelly Kahl. It's definitely a new world in terms of how you look at the ratings. The blah ratings are also producing stasis among the four big broadcasters. At the moment, NBC is off to its best start in nine years, largely due to the strength of "Sunday Night Football." But at week's end, networks often find themselves separated by differences of only a tenth of a rating point or two, with no clear leader in sight. Even with the boost from DVRs, some shows are making their way to the junk pile - just as they do every fall. CBS this week yanked "Made in Jersey," a legal drama created by former Times writer Dana Calvo. The premiere drew 7.8 million total viewers, with a paltry 568,000 added through DVR viewing. Also weak based on early ratings: Fox's drama "The Mob Doctor," the CBS sitcom "Partners" and ABC's thriller "666 Park Avenue." On the other hand, some modestly rated new series have already been rewarded with full-season orders, including NBC's comedies "Go On" and "The New Normal" and the Fox sitcoms "The Mindy Project" and "Ben & Kate." Networks may be more willing to take a flier on sitcoms than dramas, however, because comedies are cheaper to produce and can be more lucrative and longer-lasting if they grow into hits. Low-rated but long-lasting shows may be TV's new normal. That's because executives are figuring how to tally up a decent-sized audience that can be sold to advertisers across every conceivable platform, from flat screens to smartphones, according to Stuart McLean of Content & Co., which helps advertisers develop programming options that fit their brands. The days of premieres and early numbers, that's fading away quite rapidly. It is about aggregation," McLean said. As for viewers, he added: "Who cares when they watch?"