The VMKernel does an amazing job scheduling CPU resources. However having a high vCPU count on VMs that idle may cause issues with the CPU scheduler resulting in high CPU Ready. If I'm not mistaken, there are some changes to the scheduler in 5.x. Memory sizing of the VM also plays a role in this type of sizing.
Sizing VMs and NUMA nodes - frankdenneman.nl
virtualTodd's Big Blog: NUMA Performance Considerations on vSphere 5
Hope this is helpful.
