Source: Buffalo Wild Wings.

Businesses that have to rely on outside factors to drive their growth should worry investors. Buffalo Wild Wings (BWLD) has to rely in part on the strength of several sports to drive results. It's no coincidence that the company produces huge revenue and earnings growth during the end of the baseball season and into the football season. That said, the company has taken charge of its own destiny, and recent results prove the strength of the brand.

This is impressive
Many investors are enamored with fast-growth restaurant concepts. One company that has caught a lot of attention is Chipotle (CMG -0.58%). Chipotle drives its growth from fast service and reasonable prices. Buffalo Wild Wings is a more traditional sit-down restaurant business that more closely compares to a company like Brinker International (EAT -0.40%).

Brinker's Chili's concept grew earnings consistently while the company expanded across the country. Now that Brinker is looking to expand internationally and become more efficient domestically, the company is more focused on cash flow than revenue growth.

Speaking of revenue growth, this is one area where few competitors can compete with Buffalo Wild Wings. In the current quarter, the company grew revenue by almost 28%. Even the impressive growth at Chipotle isn't close, with sales growth of 18%, and Brinker International showing flat revenue growth in the quarter.

As you might imagine, strong revenue growth equated to impressive earnings growth as well. However, Buffalo Wild Wings has improved its operations by serving chicken wings by the pound as opposed to by the number of wings. Since the company's costs are derived in pounds whereas individual wings can vary in weight, this allows the company to more closely match its sales to its costs. This change in serving style contributed to the company's significant increase in earnings.

Both Brinker and Chipotle reported earnings growth in the teens in the most recent quarter. If this sounds impressive, consider for a moment that Buffalo Wild Wings grew earnings by more than 65% during the same time frame. With superior revenue and earnings growth relative to two of its peers, it seems like the company should be considered a top-tier growth stock.

A key indicator
I'm a big fan of Peter Lynch's writing, and he has said that one of the key indicators of a restaurant company's growth is that its same-store sales are increasing. While Buffalo Wild Wings hasn't been as consistent as some of its peers when it comes to same-store sales, the company's results are in line with a fast-growing restaurant concept.

This quarter, the company reported that same-store sales increased nearly 5% at company-owned stores and just under 4% at franchised locations. It's true that Chipotle reported same-store sales growth of better than 6%, but Brinker and companies like Panera Bread reported comps that were either up or down around 1%.

While Buffalo Wild Wings didn't report the strongest same-store sales growth, investors should be excited for the next two quarters at least. With the meat of the NFL and NCAA football seasons upon us, and upcoming bowl games and playoffs, Buffalo Wild Wings should continue to see strength in its same-store sales numbers.

One weakness that should improve over time
Investors should keep an eye on Buffalo Wild Wings' relatively weak free cash flow. Some investors say that cash flow doesn't matter for growth companies, but a lack of cash flow could hurt the company's ability to expand at its intended pace.

One way for investors to compare companies when it comes to cash flow is by looking at free cash flow per dollar of sales. However, using core free cash flow (net income + depreciation – capital expenditures) is a more direct comparison. Using this metric eliminates some of the non-cash changes on the cash flow statement.

In the last quarter, Buffalo Wild Wings reported core free cash flow of just over $0.01 per dollar of sales. By comparison, Brinker International generated $0.05 of free cash flow and Chipotle produced $0.13. As you can see, Chipotle's far more efficient operations are generating much more cash for shareholders relative to Buffalo Wild Wings and others.

The good news is that Buffalo Wild Wings operates less than 1,000 locations relative to more than 1,500 locations at Chipotle and Brinker International. As Buffalo Wild Wings continues to expand, the company will be able to spread its costs over a larger base and cash flow will improve.

Though Buffalo Wild Wings' stock isn't as cheap as it once was, given the strength of the company's operations, investors should keep an eye on this fast-growing concept. Investors willing to expose their "wild" side may want to slowly buy into the stock with an eye toward adding more money when inevitable pullbacks occur.