It looks to me from that graph like Wii week-on-week sales simply have a much bigger standard deviation than PS3. Wii's sales hit all kinds of spikes and valleys, probably corresponding to the erratic pacing of major releases and major gift-giving seasons. PS3's sales, by contrast, are low but rather steady. Wii hit a similar trough in week 10, which was followed by a peak just a few weeks later. I wouldn't be predicting anything from this graph unless you get a good, solid 6-8 weeks of relatively low sales.