Is their an API for the following NFS per client stats. IT looks like this command has been moved to hidden statistics-v1 in 8.2. Looking through the perf objects I do not see any objects that correlate to the object "client"
Unfortunately, there are no client stats accessible from the perf APIs. I talked with the development manger, and it is being worked on for a future release. The current granularity is node and vserver. Please look at this post for the nfsv3 vserver instances. There are also node instances for nfsv3:node counters.