The CW has finally pulled the plug on Media Rights Capital’s Sunday night time buy, ending an experiment that had quickly soured.

The pact, unveiled in spring, at first looked good on paper: It gave the CW a chance to get out of programming Sunday nights, where it had been dormant for years. MRC got primetime real estate to showcase its wares. And top CW station affiliate group Tribune got a safety valve, in case those CW shut-down rumors came true.

It all fell apart Thursday. In a letter to affiliates, the CW announced that it was terminating its deal with the programmer and reclaiming the night, where it will now run off-net series and an MGM movie package.

Given the goose egg Nielsens that MRC was producing on Sunday night, such a falling out was inevitable. But according to insiders, the CW finally slammed the door after MRC failed to keep up with its payments to the netlet. The block was already dragging down the CW’s weekly ratings, and wasn’t going over well with affils.

The payment problem was the final straw: It’s believed the CW was able to yank MRC off the night earlier than contractually possible because it hadn’t been fully paid. (A source close to MRC disputed the payment issue, calling it “categorically untrue.”)

Blame the ratings, but also blame the economy. MRC was able to rush its programming on the air in the fall, despite having just struck a deal for the CW time buy last spring. But the company wasn’t able to get in on the upfront marketplace — which turned out to be a critical mistake, as it lost out on millions of guaranteed dollars — and as the economy soured, ad dollars disappeared.

“The scatter market, which MRC was completely reliant on because of its late start, is frozen right now,” said one exec familiar with the situation. “You can’t get money in scatter to save yourself. … In a regular economy maybe you would have seen a different outcome.”

One insider noted that the Dow Jones Industrial Average was still over 12,000 when the deal was announced. When it fell apart Thursday, the stock market had slid well below 8,000. Some have also blamed MRC’s decision to launch its sked late, among other issues.

“It was the perfect storm of bad luck, bad timing and bad decisions,” said one insider. “It was a tsunami of bad things going down.”

An MRC spokeswoman, meanwhile, disputed the CW’s assertion that the relationship had been completely severed.

The spokeswoman said the company was still continuing negotiations with the CW about reviving the programming block at another point. Talks are centered on programming, timing and payments, she said.

In any event, viewers didn’t pay much attention to the block. Season to date, the MRC block was averaging 1.04 million viewers, down 42% from last year (when the CW bombed with its own fare). Among adults 18-49, the aud (older than the CW’s younger 18-34 bent) that the block was supposedly targeting, the shows averaged a 0.4 rating/1 share — down 50% from last year.

In a letter to affiliates, CW chief operating officer John Maatta said the Sunday night results were “below expectations.”

“The MRC shows are simply not working,” Maatta told affils. “To that end, we have made a business and programming decision to protect our network and your local interests on Sunday for the remainder of the season.”

The MRC shows will leave the network after Sunday. Starting Nov. 30, the CW will program the night with off-net fare from CBS Paramount and Warner Bros., as well as a movie package from MGM.

Netlet is dusting off the run of CBS’ cult fave “Jericho,” which will air Sundays at 7 p.m., followed by the movie at 8.

During the CW’s “Easy View” block, the net will air season one segs of “Everybody Hates Chris” and “The Game” in the 5 p.m. hour and back-to-back season two episodes of “The Drew Carey Show” in the 6 o’clock hour.

“Our plan is to program Sunday with distinctive, first-rate programming that can quickly stabilize the night,” Maatta said.

As for the remaining MRC on CW programming, it’s believed MRC is shopping around the Bob Saget sitcom “Surviving Suburbia,” a half-hour that was originally slated to launch this fall but had been pushed to spring. Nets pitched include ABC, CBS and NBC, but no deal is in place.

Meanwhile, the production company had already put its two CW Sunday dramas, “Easy Money” (which scored decent reviews from critics) and “Valentine,” on hiatus. At the time, the company said the move was pre-planned. But it’s believed MRC wanted to wait and see if the shows improved before spending any more money. The fate of reality show “In Harm’s Way” and the acquired Canadian skein “4Real” was unclear.

The MRC deal was originally crafted by MRC TV prexy Keith Samples and Tribune TV topper Ed Wilson. Tribune was looking for a safety net in case the CW folded — as was more heavily rumored last year — and also programming that would be more compatible with its stations’ 10 p.m. newscasts.

But with the MRC lineup failing to catch on, Tribune has more recently distanced itself from the deal. Meanwhile, Samples and MRC parted ways at the end of the summer due to creative differences over how the company’s TV division was operating.

MRC TV has had a busy year, landing countless broadcast and cable projects. Beyond the CW fare, MRC recently launched the Lifetime sitcom “Rita Rocks” and animated HBO comedy “The Life and Times of Tim.”

Production company is also behind ABC’s upcoming animated laffer “The Goode Family” and Comedy Central’s “Krod Mandoon and the Flaming Sword of Fire.”

With such a hefty slate of freshman series in MRC’s inaugural year, some industry execs have wondered whether the company has bitten off more than it can chew. (Some liken its situation to that of Artists Television Group, which similarly sold several series in its first year, only to be hit hard financially when none of those shows survived.)

MRC, however, has said that it’s well funded — indeed, it closed a three-year, $350 million revolving credit facility with a syndicate of banks led by J.P. Morgan Chase and Comerica earlier this fall.

Despite the MRC-CW failure, most pundits believe time buys such as that will become a more common part of the network landscape. (Several networks already farm out their Saturday skeds.)

“The first one didn’t work, but there will be more to come in the near future,” one exec said.