NEW YORK – The “ER” that exits television with its final episode Thursday on NBC is a shadow of its former self, stripped of the star power and buzz – and a majority of viewers – from its heyday.

Kind of like NBC itself, when you think about it.

When “ER” debuted in the fall of 1994, NBC was the must-see king of broadcast television, its schedule filled with classics like “Seinfeld,” “Friends,” “Frasier,” “Homicide: Life on the Street,” “Law & Order” and “Mad About You.” Advertisers paid a premium to reach its desirable – and large – audience.

The NBC of 2009 is a fourth-place network struggling to find its place. Last week, the penultimate episode of “ER” was the network’s most-watched show with 10.4 million viewers, ranking it No. 20 in prime-time. That’s less than a third of what “ER” averaged every Thursday in its peak second season.

NBC’s fall came from a combination of poor decisions and inevitability, putting it in a down cycle from which there’s no guarantee of recovery.

“It’s a different industry than it was when ‘ER’ started,” said Garth Ancier, one of eight men who have led NBC’s entertainment division over the past 15 years.

There were no DVRs when “ER” started, let alone opportunities to watch TV programs over the Internet or on DVD. The gaming industry was in its infancy. The average American home received 41 stations in 1995 and 119 in 2007, according to Nielsen Media Research. Cable stations once content to air reruns now produce award-winning original series.

With so many more options, NBC’s prime-time audience dropped from an average of 16.5 million in 1994-95 to 8.1 million this year, Nielsen said. While that doesn’t make NBC unique – ABC actually lost more viewers during that stretch – it speaks to a diminished influence.

The 15-year tenure of “ER” illustrates one of NBC’s problems: The network generally stuck with signature shows for too long and had little worthwhile to replace them.

Unless, of course, you considered “Joey” a fair trade for “Friends.”

It’s an understandable strategy – why trade a proven hit for a question mark, even if you know that hit’s best days are behind it? Among its target audience of young viewers, NBC was on top for eight of nine years between 1995-96 through 2003-04. Almost by definition a network becomes complacent in this position, said Marc Graboff, NBC entertainment co-chairman.

With its audiences and profit margins shrinking, broadcast networks began relying on cheaper reality shows. Between “Survivor,” “Who Wants to Be a Millionaire” and “American Idol,” CBS, ABC and Fox all had signature hits that changed their fortunes. Nothing on NBC approached that level.

After several years of stability beneath Warren Littlefield and Don Ohlmeyer, NBC’s entertainment division began rapid-fire management changes, with the new ideas and favorites that always follow. Again, NBC isn’t unusual, as Fox had similar churn. But it contrasts with stable CBS. Leslie Moonves has had the final word on CBS’s schedule since he became entertainment chief in 1995, even as he climbed the corporate ladder.

NBC parent General Electric Co. used to give the entertainment division plenty of freedom, but as the hits dried up, financial concerns became paramount, said Tim Brooks, author of “The Complete Directory to Prime-time Network and Cable TV Shows.”

At times, NBC programmers have seemed lost. Poor choices squandered the network’s advantage on Thursdays, once the most powerful night in television. NBC has strong Thursday comedies now with “The Office” and “30 Rock,” but their relatively narrow appeal hasn’t brought back the glory days.

Even as broadcast networks seek the largest possible audience, they often have a general focus to give them direction. ABC, for instance, is aimed primarily at women. “American Idol” aside, Fox seeks young men with adventure series like “24.” CBS is the destination for viewers who want a traditional network as they’ve known it for years.

NBC used to be the upscale network, with smart shows for smart urban viewers.

What is it now?

“The network that brings us ‘Howie Do It’ has a hard time justifying that kind of image anymore,” Brooks said.

NBC executives believe the past is a blueprint for the future.

“To get back that position as being an industry leader is very important to us,” Graboff said. “It’s part of our heritage.”

NBC has sought to weather the hard times with savvy business decisions. Series like “The Office” may not have a broad audience, but NBC has aggressively marketed the series on iTunes and on DVD, and sells show-related merchandise. Since NBC owns the show, the network recently made a big score by selling the show for syndication.

NBC’s bold decision to air Jay Leno at 10 p.m. each weeknight this fall could potentially be a stroke of financial genius, and allow the network to concentrate better programs in the remaining two prime-time hours.

But don’t expect a network to command the profit margins and rich lineup of scripted shows of the glory years. NBC spent millions for the series “Kings” and it debuted last month with fewer viewers than the show NBC ran in the same time slot a week before – a special with clips of old “Saturday Night Live” routines. That’s a powerful spending disincentive.

Yet a true revival can’t be done on the cheap. NBC is going to have to experiment and spend money in order to retrieve the you-have-to-see-this buzz that it long since lost, Brooks said.

Graboff promised to try.

“We’re in a rebuilding phase cyclically,” he said. “A cyclical rebuilding phase is a common thing – it happens to everyone …When you’re in this phase you’re willing to take more chances and that generally results at some point in a breakout television show.”

Wheel the patient into intensive care.