What exactly does that graph show?
1) The Y axis for the graph seems to be "Ken's Tech Tips Index (Monthly)". That's completely meaningless - what on earth does it mean?
2) Is the Y scale linear or logarithmic? (I guess linear, because that's the default you'd use if you don't know what linear and logarithmic mean). Also, the lack of labels on the Y axis makes it hard to read.
3) The Y axis is labelled "(Monthly)", yet the graph appears to be a smooth curve. Are the parts between the month points real data, or are they made-up pretty wavey lines? (I suspect they're made-up pretty wavey lines. As other people have said, the graph seems to respond just before price rises, which is consistent with made-up data but not with real data).
4) What's the sample size for this data? And is it a random sample? If it's not a random sample, what are the biases? Is this biased towards the type of people who will compare prices online and find the cheapest deal? If so, then OF COURSE the data will show price sensitivity!
... ok, after looking at the linked article, the graph shows ( (number of customers joining the network) / (number of customers leaving) * 100). I.e. it's in percent. This makes the 100% point very important, as it's where a network switches from shrinking (score below 100) to growing (score above 100). So the lack of a horizontal line at 100% (or even a mark on the Y axis!) is a grave error.