Boyd Gaming (NYSE:BYD) shares climbed 16% yesterday following the casino operator's impressive fourth-quarter earnings report. They're up another 4% to over $19 today.

The source of the enthusiasm is Borgata, the company's 50-50 joint venture with MGM Mirage (NYSE:MGG). The resort casino opened this past July, immediately establishing a presence in the Atlantic City market. Borgata delivered $122 million in gaming revenue in the fourth quarter -- second only to Caesars Entertainment's (NYSE:CZR) Bally's Park Place.

With the boost from Borgata, Boyd's fourth-quarter earnings before interest, taxes, depreciation, and amortization (EBITDA) climbed 14.5% to $75.1 million, with the 50% share of Borgata accounting for almost a quarter of the results. That made up for the impact of higher gaming taxes on properties in Illinois, Indiana, and Las Vegas.

With one bold move, Boyd has redefined itself. Known as a locals casino operator with its Sam's Town brand, collection of downtown Las Vegas properties, and riverboats, it has demonstrated that it can develop and operate resort-style casinos. This point is so important that it devoted half of its press release to Borgata.

Boyd had been a pure value player, expanding into new markets by snapping up sub-premium properties at extremely attractive prices. Just last month, it announced the purchase of Harrah's (NYSE:HET) Shreveport property for $190 million, a deep value at 4.2 times to 4.4 times EBITDA. Like most of Boyd's other properties, the Shreveport casino is a second-best in market, behind the Horseshoe riverboat directly across the river that Harrah's is in the process of acquiring.

But along with Borgata's success, Boyd has confidence in the future of its famed -- and aged -- Stardust property on the Las Vegas Strip. Next year, Wynn Resorts (NASDAQ:WYNN) will open the highly anticipated Wynn Las Vegas across the street, increasing the value of that end of the Strip. At that point, Boyd said on a conference call (transcript provided by CCBN), it will release definitive new development plans for the Stardust and the 60 acres on which it sits.

The gist of it is this: Aside from Borgata, Boyd is not a premium player in any other market -- yet. That, along with its brand image, should change as the company develops more resort-style properties over the coming years. When that happens, the stock could shift from a strict value play to a more premium play along the lines of Mandalay Resort Group (NYSE:MBG) and MGM Mirage.

If there's a concern at this point, it's that this shift is already becoming reflected in the stock price. With the company trading at about seven times 2004 EBITDA, it's clear that investors are already catching on.

Give us your take on the Boyd Gaming discussion board -- only at Fool.com. Jeff Hwang can be reached here.