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 analyst upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of Cliffs Natural Resources (NYSE:CLF) slipped about 1% in pre-market trading after Wells Fargo downgraded the iron-ore miner from market perform to underperform.

So what: Along with the downgrade, analyst Sam Dubinsky lowered his price range to between $12 and $14 (from $19 and $24), representing as much as 38% worth of downside to yesterday's close. While contrarians might be attracted to Cliffs' share-price slide in recent months, Dubinsky thinks there's plenty of room to fall given his view of accelerating weakness in iron-ore prices.

Now what: Wells Fargo lowered its 2014 earnings-per-share view for Cliffs from $1.75 to $0.55. "Global spot pricing is weakening due to a slowdown in China, excess inventories, and ramping supply from low cost miners," Dubinsky said. "While we like the new CEO and see value in shares if management sells high cost assets, we are not yet convinced efforts will be enough to keep shares afloat." Of course, with the stock now off more than 30% from its 52-week highs and boasting a 3% dividend yield, those concerns might provide resource-savvy Fools with a solid long-term opportunity.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.