Well-chosen small-cap stocks can deliver years of outsize gains to investors. However, the best of these businesses often come with premium price tags, which can lower the returns for those who buy at those elevated prices. There are, however, rare occasions when the stock of an excellent business goes on sale. Today, we have one such opportunity with Boston Beer (NYSE:SAM).

Image source: Boston Beer.

After a rough 2015 and further weakness so far this year, Boston Beer's shares now sit more than 50% below their all-time highs of January 2015. Slowing sales of the company's core Sam Adams brand beer and multiple analyst downgrades have skunked the stock, leading short-term-oriented investors to bail out in droves.

Therein lies our opportunity, as we can now buy shares in a quality business at a bargain price.

Boston Beer -- led by founder, chairman, and brewing legend Jim Koch -- is a pioneer and leader in the craft-brewing industry. Thanks to the popularity of its Sam Adams line of beers, the company has built a powerful distribution system that allows it to acquire shelf and tap space for its newest products. That's helped Boston Beer's Angry Orchard become the top-selling brand in the fast-growing hard-cider category and should also help to spur adoption of its new hard soda drinks and Nitro line of beers.

Image source: Boston Beer.

But competition has been intensifying in the craft-brew arena, with industry behemoths such as Anheuser-Busch InBev and Constellation Brands snapping up promising craft brewers in recent years. In addition, small brewers continue to spring up and compete for the chance to quench beer drinkers' thirst, with more than 4,000 operating in the U.S., according to the Brewers Association -- a number that Koch thinks can eventually rise to 10,000. 

This competition has taken a toll on Boston Beer's results in recent months, with core shipment volume falling 6% year over year to 830,000 barrels in the first quarter. "We believe Samuel Adams has lost share due to the increased competition and continued growth of drinker interest in variety and innovation," Koch said in a company press release.

But innovation is where Boston Beer excels. In a recent interview with USA Today, Koch highlighted Boston Beer's strength in this area.

We have always felt a drive to push boundaries, to create new beers and new beer experiences. Ultimately that has been one of the keys to our success, a relentless drive to do everything better, including coming up with new styles of beer. We just came out with the Sam Adams Nitro project, which is opening up white space in beer by taking some important styles of beer and taking the carbonation out of them and replacing them with nitrogen to make them smoother and creamier and to bring out different flavors in the beer.

Image source: Boston Beer.

To further spur innovation, the company established Alchemy & Science, a craft-beer incubator, in 2011. That's led to successes such as the Traveler Beer Company and the Coney Island brand, which Alchemy & Science acquired in 2013. The venture has become a significant portion of Boston Beer's business, with Alchemy & Science's sales accounting for approximately 7% of the company's total net sales in 2015, up from less than 2% in 2014. That's a number that should continue to rise as A&S expands distribution for its fast-growing brands in the years ahead.

All told, Boston Beer still has tremendous room for growth, with the company accounting for only about 1% of the beer sold in the U.S. last year. Yet investors appear to be projecting that Boston Beer's recent struggles will persist indefinitely -- something I believe is unlikely thanks to its popular brands, strong distribution system, and innovative culture. At a current market cap of $1.95 billion, the stock can be had for 2 times sales and only 10 times enterprise value to EBITDA, a bargain compared with Boston Beer's historical valuation and a price many larger competitors would gladly pay should Koch ever decide to sell. That's a risk/reward situation that patient, long-term investors should find attractive, and a good reason to take a sip of Boston Beer's stock.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.