Actually it's quite easy to argue with those figures. The whole business world involves degenerating multidimensional environments into single dimension numbers, then arbitrarily adding dimension to the numbers by claiming why they are the way they are, what they'll be in the future, and how they're going to get there. It's a lot of Voodoo magic if you ask me. There is too much subjective human input for many of the figures to be worth much without viewing them in context.
I don't think these numbers are bad at all. In fact, I think they're promising if they're taken in context. A substantial number of Mac users were fully aware that Apple was about to release the next-best-thing and were hesitant to upgrade until such a product became available. At a microscopic level, this sort of thing happens on a seasonal basis when sales plummet before anticipated release dates. IMHO, the past year was an extended version of the pre-release-date syndrome. Even to die-hard Mac freaks, this past year it became completely obvious that the G4 platform was going nowhere fast and was outdated. Nobody wanted to purchase a PowerMac line unless they really needed to. To a lesser extent, the unavailability of software titles like Quark also kept a significant portion of Apple's customers from purchasing new hardware. However, look at Apple's laptop sales and the figures are quite positive.
So, the question that remains is "Why didn't Apple's sales plummet?". IMHO, new Apple customers picked up the slack (i.e. like myself and a few other people I know). The coming year will definitely clarify the situation, as the G5 platform will be out and there will be no excuses for current Apple customers not to participate in a product refresh. I don't even think I'm making a bold prediction when I say that I think the coming year will see Apple's sales of PowerMacs double over the past year's figures.
I hope I don't even need to mention that extrapolating marketshare from unit sales is an imprecise science. Ask a Mac user how long he/she keeps his/her computer before upgrading to a new one. Compare that to the typical PC user. For some reason, Mac users tend to keep their computers longer than their PC counterparts. For the sake of simplicity, let's say in the time that a Mac user owns one Mac, a PC user owns two PCs. You still only have two people but if you apply this marketshare Voodoo, it'll appear as though there are two PC users to the one Mac user. It's almost as bad as determining how many Windows users there are by looking at sales of Windows. There are way more Windows users than there are sales of Windows. Even so, there are still many people included in business figures as Windows users that formatted their computer and installed an alternative OS.
Of course, my next point is anecdotal but _ALL_ my friends are impressed with my Apple laptop. There is one for sure who will buy his first Apple very soon, and the others are thinking seriously about switching when it comes time to buy a new computer. I would say there are 8 potential new Mac users right there - half will very likely follow through. The more they see me use it, the more they realize that it's no longer the crippled platform it once was. And all have come away wishing they could use OS X instead of Windows, after using it for the first time. That's pretty impressive to me as none are really power users, so their reasons for using OS X are not due to its UNIX underpinnings (they don't care), or because it's simple to use, but because they dig the way everything works. Additionally, they had to put up with years of myself making fun of the crappy Mac platform. So their perception of the platform is biased toward the negative.
So, time will tell. Apple has been dying for the past 15 years according to the critics. I for one think they'll be in a substantially better financial position a year from now than they are now.