VMware overstating VMs consolidation ratio?

Quoting from IT Business:

Most Canadian enterprises are achieving about half the consolidation ratios per processor that vendors claim virtualization will bring, according to a report published by Info-Tech Research on Wednesday.

visits or in-depth phone interviews with more than 30 companies two months ago, Info-Tech concluded that vendors are exaggerating the number of servers that can actually be consolidated through virtualization, inflating the technology’s potential…

Read the whole article at source.

While not expliclty said, this article is clearly referring to VMware, the only virtualization vendors who indicates in official documentation average expected VMs/core consolidation ratio, depending on chosen product.

In years Microsoft never declared such value, which highly depends on several factors but it’s critical for customers when facing return on investment calculations.
Xen development team and commercial companies offering it, XenSource and Virtual Iron, didn’t as well. And neither the russian start-up Parallels ever expressed a position about this topic, even if they are still focused only on desktop virtualization where this value is not fundamental.

While it’s possible VMware reported a too optimistic value, it’s worth to remember that a certain VMs/core ratio is achievable only approaching a virtualization project with enough knowledge: the most delicate part in server consolidation projects is recognizing physical server candidates for P2V migration and architecting the virtual datacenter accordingly.

Skilled virtualization architects know that migrated services need to be arranged in a rational way inside virtualization platforms, trying to balance low and high workloads together.
Most of times missing suggested consolidation ratio depends on a poor design.