They definitely needed to dot their I's in the article, but I see what they are getting at. While the 360 and PS3 are performing better or equal to what they did last year, the Wii has seen a significant dropoff. The loss in revenue over last year when considering the entire console market is not due to loss in revenue from the 360 and PS3, but because the Wii is not generating the ridiculous amounts of revenue it was a year ago.
As for the narrowing its lead comment. They are basing that on how much the Wii is selling as a percentage over its competition not on a total consoles sold over the lifecycle of this generation. Yes their lead is still increasing on total consoles sold, but they are doing it at a much slower rate then they were in the past.
When you look at it from a finance perspective, which is what Bloomberg does, finance is all about growth and potential increase in revenue and profits. That is why people buy stock. If Sony is increasing their revenue, and Microsoft is holding steady, and Nintendo is decreasing in revenue, then Sony is the winner followed by MS, and Nintendo is trending downwards. It does not matter that Nintendo is making the most profit, or selling the most consoles, it just comes down to that their growth as a company in the short term is doubtful, and therefore there is no reason to expect the price of their stock to increase. Again they do not base this on total consoles sold as some sort of measure of growth, but the revenue and profits compared to the previous year.