Q2 is a good quarter to portray the companies success year-over-year.
After spending, literally billions, Lumia sales haven't received any success for Nokia by Q2 '12. This is one good piece of data to know.

That means the devices were either poor products, or overpriced, otherwise the market had other preferences. In Nokia's case it was all of the above.

Nokia didn't undercut its phone's prices to make purchase incentive (at least not until late '12). Nokia's devices weren't as advanced as the competition (no large screens, great battery life, killer features etc etc), at least not until the 1020. But more than that, the public wasn't warm to the Windows Phone ecosystem.

Let's fast forward a year, to Q2/13.
Nokia has doubled its shipments. Its greatly reduced its advertising/R&D costs.
It is beginning to bare the fruit of its labour. However the figures are still low, meaning anythings possible.... but if the figure continues at current pace, it leaves Nokia with 12M sales which is "sustainable" for a firm of this size. Something like 30M would be a more "healthy" state for an OEM of this calibre.

Now lets have a look at BB.
Starting with Q2/12 they are caught in their slouch from a "sustainable" 11M figure down to barely 8M. The lag to produce their new ecosystem (BBX) costed them 1.5 years... this impeded their business.
Regular business would bankrupt at such happenings but BB is large enough to survive it.
They did a tremendous job of keeping it alive, however the competition has been too strong.

Fast-forward a year, now BB ships 7M devices.
That hurts a company of this size. It would have to get smaller, otherwise its simply not sustainable. Here BB is hoping for another 6-12 months of 6-8M figure sales. But hoping they bare the fruit of their labour as Nokia is (only just) beginning to.
If such a thing happens, BB could find itself selling 12M devices a quarter, far from its previous victories... yet a sustainable figure.

At which point, Nokia and BB would be at a deadlock... yet far from their competition of Apple and Samsung. They would be competing with the likes of LG and SONY both selling between 8 - 10M units per quarter... whereas HTC is in grave danger as its constantly shipping lesser and lesser devices each quarter/year and is in the 5M figure.