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 Swift Energy (NYSE:SBOW) slipped 2% on Friday after Wells Fargo downgraded the oil and gas producer from outperform to market perform.

So what: Along with the downgrade, analyst David Tameron lowered his valuation range to $11-$13 (from $14-$17), with the midpoint representing just 8% worth of upside to yesterday's close. So while contrarian traders might be attracted to Swift's year-to-date price sluggishness, Tameron's call could reflect a sense on Wall Street that the risks surrounding the company's restructuring efforts are likely to keep pressuring the stock.

Now what: According to Wells, Swift's risk/reward trade-off isn't too appealing at this point. "The company delivered on its Eagle Ford JV earlier this year, but in our view, additional asset sales are needed to de-lever the balance sheet and provide flexibility in 2015," said Tameron. "While the company has its CLATEX assets on the market, continued delays and a disjointed package of assets leave us thinking that either the deal won't get done, or only parts of it will." Of course, with Swift shares now off about 30% from their 52-week high and sporting a price-to-book ratio of 0.5, the downside might be limited enough to bet on management's ability to unlock more value.