"Frustrating" may be the best descriptor for Riverbed Technology (UNKNOWN:RVBD.DL). Shares of the network efficiency expert fell more than 17% Friday after the company issued worse-than-expected guidance. Co-founder Steve McCanne is also leaving the company for charitable pursuits.

We've seen this sort of trouble before. Riverbed slumped 28% last April, when management guided to second-quarter results that were well short of estimates. At the time, executives blamed an in-process product transition that most thought to be resolved heading into last week. Now, at least some of the bulls have turned bearish.

Is the growth story over? Tim Beyers of Motley Fool Rule Breakers and Motley Fool Supernova says the clues are in the financial statements, where you'll find a key metric more than doubled. What is this hidden metric? Tim explains in the following video. Please watch, and then be sure to leave a comment to let us know what you think.

Fool contributor Tim Beyers is a member of the Motley Fool Rule Breakers stock-picking team and the Motley Fool Supernova Odyssey I mission. He owned shares of Riverbed Technology at the time of publication. Check out Tim's Web home and portfolio holdings, or connect with him on Google+Tumblr, or Twitter, where he goes by @milehighfool. You can also get his insights delivered directly to your RSS reader.

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