"After facing lackluster results from Windows-based tablets featuring its Z-01 and Z-60 chips"
I own a Z chip, and I can tell you the lackluster sales performance is AMD's own fault.
A rehash of a chip from three years ago, without even a MHZ upgrade is no way to stand out against Intel on the launch of Windows 8. On release these were great chips, three years later they are getting long in the tooth and a new Atom can outperform them in virtually every way (cpu, power, gpu.)
It's not that performance is especially bad on these chips, its that AMD canceled their replacement and attempted to fill the gap by rebadging their existing chips without changing the silicon in the least.