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 Molson Coors Brewing Company (TAP -0.75%) gained 1.5% today after Bank of America upgraded the beer giant from underperform to outperform.

So what: Along with the two-notch upgrade, analyst Bryan Spillane boosted his price target to $80 from $55, representing about 13% worth of upside to yesterday's close. While contrarian traders might be turned off by Molson's price strength during the past year, Spillane's call could reflect a sense on Wall Street that its improvement potential still isn't fully baked into the valuation.

Now what: According to B of A, Molson's risk/reward trade-off remains rather attractive at this point. "Key factors to consider are : 1) Prospects for a solid performance in Europe, potential improvement in the US tied to improving economy, easier comparisons and Miller Coors marketing initiatives, 2) improvement in cash flow and total shareholder returns enabled by a broader application of the companies PACC (EVA like) model, 3) Canadian cost savings initiatives should begin to have more of an effect later in 2014 and into 2015, and 4) Increased appreciation in the market for the value (to TAP) of the Miller Coors JV including the accretive scenario of TAP buying out its partner," said Spillane. More important, with Molson continuing to sport a reasonable forward P/E in the mid-teens, and a solid 2% dividend yield, the downside might still be limited enough to bet on those catalysts.