Hi,
Microsoft finally answered the question I had :
Perfmon provides relative information and hence we cannot judge the performance of disk / CPU directly.
This value processor queue length shows number of threads in the processor. Since there is only one queue for all the processors in a CPU , the value you see here in perfmon has to be divided by the number of processors on the machine. Usually a value <10 is a good one.
Since my servers had 8 vCPU I had to devise by 8 the value showed in the SCOM console and it was way below 10, which is fine.
Thanks