While Fools should generally take the opinion of Wall Street with a grain of salt, it's not a bad idea to take a look at particularly stock-shaking analyst upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of Nimble Storage (NYSE:NMBL) soared 8% this morning after Morgan Stanley upgraded the flash storage technologist from equal-weight to overweight.

So what: Along with the upgrade, analyst Katy Huberty planted a price target of $38 on the stock, representing about 36% worth of upside to yesterday's close. So while momentum traders might be turned off by Nimble's sharp pullback in recent months, Huberty's call could reflect a sense on Wall Street that the concerns surrounding its growth trajectory are becoming overblown.

Now what: According to Morgan, Nimble's risk/reward trade-off remains rather attractive at this point. "We raise revenue estimates above consensus and upgrade NMBL to OW with a $38 PT," said Huberty. "Our recent meetings with management highlight: 1) new products will increase enterprise penetration, 2) Nimble's competitive moat is intact and sustainable, and 3) gross margins remain stable." More importantly, when you consider Nimble's rock-solid balance sheet and still-beaten stock price, the downside seems limited enough to bet on that upbeat outlook. 

Brian Pacampara has no position in any stocks mentioned. The Motley Fool recommends Apple. The Motley Fool owns shares of Apple. 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.