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

What: Shares of Juniper Networks (NYSE:JNPR) slipped about 3% on Thursday after Mizuho downgraded the network equipment technologist from outperform to neutral.

So what: Along with the downgrade, analyst Matthew Hoffman lowered his price target to $26 (from $32), representing just 3% worth of upside to yesterday's close. So while contrarian traders might be attracted to Juniper's price sluggishness in recent months, Hoffman's call could reflect a sense on Wall Street that near-term sector headwinds will continue to pressure the shares. 

Now what: According to Mizuho, Juniper's risk/reward trade-off is pretty unappealing at this point. "Over the past few weeks datapoints have become more mixed regarding domestic capex as reports AT&T may reconsidering its CY14 capex budget have surfaced (MasTec disappointed, Ciena beat)," said Hoffman. "After conducting a series of industry checks, we are now less constructive on 2H14 domestic U.S. spending as it appears both AT&T and Sprint are becoming more conservative with near-term capex." When you couple that downbeat view with Juniper's near-30 P/E, it's tough to disagree with Mizuho's cautious stance.