A brand is nothing more than a label, associated with a certain company's goods and services. A brand's value is tied to the perceived quality of the goods and services under said brand. Since Microsoft is (soon to be) 3rd place in console sales, and 2nd place in revenue (from gaming), it is obvious that the quality of their goods and services is not perceived as very high by the average gaming customer. In a couple years Xbox will lag behind even Nintendo in gaming revenue simply because they will have to start a new generation, while Nintendo will be at the peak of their own console cycle.
Furthermore, both Nintendo and Sony have multiple game IPs under their brands that sell 10+ million. Microsoft has none. Some might argue that Minecraft would count, but Minecraft is available on every platform, and thus isn't associated with the Xbox brand by the majority of consumers. Whether it truly falls under the Xbox brand or not is beside the point. And since it isn't associated with Xbox, the value of the Minecraft IP doesn't add to the perceived quality of the Xbox brand. Neither Halo, nor Gears, nor Forza have sold 10+ Million copies.
And let's not even get into how the latest batch of critical duds under the Xbox brand have devalued it. Perhaps those games are enjoyable, but when so many consumers see really low review scores, the perceived value of Xbox branded games is lowered.
The whole notion of Xbox being the highest valued brand in gaming is just ludicrous on multiple levels.
