a good start is often the CV Documentation here:
In your case i would say the read performance of the client is relatively slow (disks?) and probably the bottleneck. Also resulting in the writer (backend storage) waiting for the data from the reader so network is also not a bottle neck here.
Upper part are client values, lower part are mediaagent/backend values. Thus buffer allocation on the client is fast, compression of the data on client side is also fast, so probably no cpu bottleneck. Most of the time the values listed there are pretty self explanatory.