Image source: Boston Beer.

Boston Beer (SAM -1.28%) just reported fourth-quarter results, beating Wall Street's revenue estimates but falling short on the bottom line. Shares fell as much as 8.5% in after-hours trading.

The specialty beer brewer reported GAAP earnings of $1.33 per diluted share on $205 million in sales. That's a 6% year-over-year earnings increase and 29% higher sales. Analysts were looking for earnings of $1.51 per share on revenue near $193 million.

Looking ahead, Boston Beer's earnings guidance for fiscal year 2014 centers around $6.20 per share. The high end of management's projections falls below the current Street view at $6.47 per share.

Like other beer specialists, Boston Beer reports a metric known as depletion growth. Depletion refers to the rate of product shipments from distributors to consumers, stores, and entertainment establishments, and is not always the same as shipments from the producer to distributors.

In the fourth quarter and full year of 2013, Boston Beer's depletions grew 20% and 23%, respectively. In other words, revenues outgrew depletions in the fourth quarter. In 2014, the company expects a depletion rate between 16% and 20%.

Management kept a stiff upper lip, nonetheless.

"In the fourth quarter, our depletions growth remained strong and benefited from growth in our Samuel Adams, Twisted Tea and Angry Orchard brands," said Boston Beer CEO Martin Roper. "With the launch of several new beers, and our increased investment behind Twisted Tea and Angry Orchard, we believe we are well-positioned to maintain our momentum."