Cracks in Under Armour

One buyer, who bought Under Armour lacrosse gear last spring, said "these were great for boys and men, and we had to go back and order more." Another said kids playing baseball and football "want to wear" Under Armour. "It's not a fad, it's good technical gear."

That being said, I do think it's important to call attention to issues when a stock may be priced as if the company will hit every pitch out of the park.

"Seven or eight months prior, anything with a UA label would sell through the door," notes Farmhouse's J.P. Mark, who also does not hold positions in Under Armour or Nike. "This is the first instance of buyers telling us there are problems."

Earlier in the month, Under Armour shares slid after the company warned that second-quarter earnings would be below expectations because of marketing expenses. The 9%, one-day selloff illustrates how quickly investors will dump a stock when expectations are high.

Shareholders of longtime highflier Whole Foods (WFMI Quote) saw just what can happen when the growth story comes into question. Shares are off 14% since the grocery chain's disappointing earnings report.

High P/E growth stocks can be tremendous investment vehicles as long as the story is intact. But when doubts start to arise and ultimately problems appear, the stocks can get pounded like a Kei Igawa fastball.

So rather than considering this column headhunting, think of it as a little chin music, designed to back you off the plate and think about what's coming next.

"In a growth story, when you grow the top line with product extensions and then there is weakness in those products, that changes the story," says J.P. Mark. "Expectations are pretty lofty. At some point it's going to catch up to the stock."

I concur.