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 Activision Blizzard (NASDAQ: ATVI) popped 5% in premarket trading Thursday after Bank of America upgraded the video game giant from neutral to buy.

So what: Along with the upgrade, analyst Justin Post raised his price target to $25 (from $20), representing about 21% worth of upside to yesterday's close. So while contrarians might be turned off by the stock's strength over the past year, Post's call suggests that Activision's lineup of upcoming games give it plenty of room to run.

Now what: B of A now sees 2015 EPS for Activision of $1.38, up from its prior view of $1.31. "We see several upcoming title catalysts including a Diablo 3 expansion (3/25), Destiny (9/9), a WoW expansion (2H14), Hearthstone (out of Beta this quarter), and an online version of Call of Duty in China (possibly 2H14)," said Post. "Given this title slate, we see greater relative revenue and earnings upside potential than for [Electronic Arts (NASDAQ:EA)]. We think Destiny could be 'the' title of E3 and a top game for next-gen console players this year. Also, a WoW expansion pack should aid sub trends." When you couple those bullish prospects with Activision's still-reasonable forward P/E of 15, it's tough to disagree with B of A's upgrade.  

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.