How much do AAA franchises like Mario or Call of Duty really effect the over all landscape of month to month video game sales? The folks over at statista.com have answered this question with a great infographic.
As you can see from the infographic, since the beginning of 2009, which was when the economy went south, if there isn't a AAA franchise out, then the sales are terrible. And even that is no guarantee, look at November of 2009, Call of Duty: Modern Warfare 2 came out that month but it still could not do as well as Call of Duty: World At War the year before. So it is pretty much the rule, but every rule has at least one exception.
So what can we really take from this infographic? I took that in the last 6 1/2 years, there has been no better time for video games than the period between June of 06' and February of 09'. during that time there was nearly continuos growth in the industry. Most of it, I assume, was driven by new consoles hitting the shelves which creates a new customer base, which buys more games.
Also, it does seem that the AAA franchises, for the most part, do drive the sales. As you can see, since 2009, there has not been one positive month that didn't feature a AAA title. This is why things like console exclusives and early access DLC have become such a big deal.