Last month, I wrote that Darden Restaurants (NYSE:DRI) has been "going through a rough patch along with the entire restaurant industry as cash-strapped consumers increasingly opt for more affordable, fast-casual options like Chipotle Mexican Grill."

As a result, I was intrigued that this "rough patch" had dragged shares of Darden down near 52-week lows, with the stock then trading for less than 14 times trailing earnings and offering a dividend yield north of 4%. As luck would have it, shares of Darden have risen more than 7% since then, outpacing the broader market's return of less than 2%.

Still -- as anyone who has ever owned stocks can attest -- if there's one thing that's predictable about the stock market over the short term, it's that its swings are wildly unpredictable. Truly Foolish investors, then, should rely on looking at any given stock's underlying business with a long-term perspective in mind.

That, my fellow Fools, is exactly what makes this latest news so interesting for Darden shareholders.

If you can't beat 'em...
You see, Darden just took a page from the playbooks of its fast-casual competitors, announcing yesterday that it is currently testing a "pay at the counter" approach for lunches at two Red Lobster locations, aptly dubbing the service "Seaside Express."

The timing is curious, especially considering Darden is set to release its fiscal 2013 third-quarter earnings and same-restaurant sales for the past three months on Friday morning. With that in mind, bullish Darden investors can only hope this news isn't an attempt to preempt the fallout of disappointing results.

To be sure, fast-casual competitors have been eating Darden's lunch (so to speak) as health-conscious diners realized restaurants like Chipotle (NYSE:CMG) and Panera Bread (NASDAQ:PNRA) could offer high-quality food without demanding the better part of their lunch hours. Given the nature of full-service restaurants like Red Lobster, Darden will need to overcome multiple hurdles to allow its new service to succeed, including not just changing diners' perceptions of its brands as sit-down restaurants, but also meeting expectations of providing decent, affordable food in a reasonable amount of time.

Darden isn't the only one threatened
On the other side of the spectrum, it's been much easier for flexible fast-food outfits like McDonald's (NYSE:MCD) and Yum! Brands (NYSE:YUM) to deal with the fast-casual threat by at least attempting to convince the public of their ability to offer healthier meals. McDonald's, for one, most recently announced its healthier Egg White Delight sandwich, and has accelerated its efforts to be more transparent in providing nutrition information on its menu.

Meanwhile, Yum! Brands has implemented a healthier Fresco menu for its Taco Bell segment, dubbing it (albeit questionably) "Drive-Thru Diet." In addition, and in a more direct shot at Chipotle, Taco Bell recently hired celebrity chef Lorena Garcia to craft its new line of more wholesome Cantina Bell offerings -- which, as I noted earlier this week, are surprisingly good.

As a result, while fast-food has traditionally catered to a dramatically different customer base than Darden serves, the line separating the two is quickly becoming blurred. In the end, while I still like shares of Darden given their current valuation, I'm not holding my breath for this move to be a game-changer anytime in the near future.