So what number do we have proof of? 4.2 million sold, 5.1 shipped now? Sounds pretty good. If PS4 wasn't killing it right now there would be no story.
Also isn't this what most people wanted/thought would happen. Not much of a story. Would be if it was other way around.
Xbox One did the bulk of its sales in 2013. The demand for the system in 2014 has fallen drastically, so much so that PS4 is selling in a month what MS is selling in a quarter.
Their sales are going to look even worse over the next few months. The gap is growing, MS has met demand and oversupplied the market. They lost the most important NPD for them this year, even after price cuts and bundles. Things are trending downhill for them unless MS find a way to really shake things up.