Why look at only November? Back then anyone could look at the 2013 year to date sales ranks and see PS4 ahead of Xbox One.
And you're making the mistake of correlating the relative ranks to actual sales numbers again. PS4 dropping one slot from April to May doesn't mean it sold less, it just means something above it sold more. Since that month had a major game release like Watch_Dogs that sold like crazy it isn't strange to see it pop above the PS4 and there is no reason to conclude from that sales went down. For all we know they went up.
And you're making the mistake of correlating the relative ranks to actual sales numbers again. PS4 dropping one slot from April to May doesn't mean it sold less, it just means something above it sold more. Since that month had a major game release like Watch_Dogs that sold like crazy it isn't strange to see it pop above the PS4 and there is no reason to conclude from that sales went down. For all we know they went up.