Man I fucking love using market share as metric! Since it is a unitless number it can be used to say anything you want. So under the old model, Amazon controlled 90% of the [market for eBooks]. After publishers instituted their new pricing scheme Amazons market share fell to 60% of [the market for eBooks]. That sounds absolutely terrible!
Unless of course you realize market share is a unitless number that doesnt tell us jack shit. Before publishers changed their prices we dont know what the size of the eBook market was so we dont know what Amazons unit sales or dollar sales were for that time period. After publishers changed their prices we still dont know what the size of the eBook market was so were still unable to tell what Amazons unit or dollar sales were.
Without knowing Amazons unit or dollars sales it is impossible to know if they were materially affected by the change in publisher prices. With Apple entering the eBook retailer arena and thus bringing an eBook store to many tens of millions of iPhones, iPods, and iPads they very likely increased the overall size of the eBook market. Google also entered the fray selling books and magazines in this period of time.
Google and Apple selling eBooks likely increased the total size of the eBook market which means unless Amazons sales grew in that same period at the same rate as the total market their share of that market could only decrease. This isnt rocket surgery. Market share simply cannot show that competitors ate Amazons market share or if their share decreased from market growth. As such market sahre cant possibly be used to show that publishers changing their pricing model positively or negatively affected Amazon. This isnt about defending megacorporations but about not using stupid numbers to make definitive arguments.