By Rick Aristotle Munarriz

Maybe Green Mountain Coffee Roasters (GMCR) won't have such a rosy holiday season after all. Stifel Nicolaus analyst Mark Astrachan issued a bearish note on the java giant, sending the stock sharply lower yesterday. Shares have tumbled over 20% in the last three days.

Astrachan's channel checks show that Keurig brewer shipments from China have declined in recent months. The news contrasts with Green Mountain's conference call last month, when the company behind the Keurig single-cup brewers and the K-Cup portion packs that fuel the caffeinated sips indicated that sales are holding up well. It stuck to its near-term guidance calling for 60% to 65% in net sales growth for the entire fiscal year.

Astrachan feels that decelerating brewer shipments will result in a slowdown in K-Cup shipments.

Then again, we're only seeing part of the picture here. Bears were concerned that inventory levels were growing faster than the company's heady net sales. Is this simply a response to close the gap? Is this a natural slowdown ahead of the second generation of Keurig brewers that Green Mountain expects to introduce next summer? Is Astrachan's data also including the licensed Keurig-compatible single-cup brewers that Jarden's (JAH) Mr. Coffee and Conair's Cuisinart have been putting out? Are folks simply not buying brewers, or are they choosing different systems like the new CBTL single-cup platform that also makes espresso? Bed Bath & Beyond (BBBY) has been promoting that particular Keurig rival over older peers that have flopped in the past.

We're definitely getting mixed messages here.

This should have been a strong quarter for Green Mountain. Starbucks (SBUX) finally rolled out its K-Cups last month. Dunkin' Brands (DNKN) hopped on the K-Cup bandwagon over the summer, and even began selling Keurig brewers in some of its stores. Earlier this month, Canaccord Genuity analyst Scott Van Winkle reported that K-Cups were taking up 30% to 50% more shelf space than they did a year earlier.

What should have been a quarter of redemption is now one of questions. The volatility will create opportunities on both ends of this battle. As a shareholder, I know which way I want this to end, but we'll all have to deal with the ups and downs until those questions are ultimately answered early next year.

Longtime Fool contributor Rick Munarriz calls them as he sees them. He does not own shares in any of the stocks in this story, except for Green Mountain Coffee Roasters. The Motley Fool owns shares of Starbucks. Motley Fool newsletter services have recommended buying shares of Starbucks, Bed Bath & Beyond, and Green Mountain Coffee Roasters. Motley Fool newsletter services have recommended creating a lurking gator position in Green Mountain Coffee Roasters. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.