As well as network IO. This is why just by the load you can't tell what is going on and this is exactly the reason why I don't like it too much in production. A box should do a have a smooth 15minutes normalized load over time. (If your workload changes you can do autoscaling, I think we used the normalized load as the metric for scaling up and down).
Processes blocked on a network socket should be Sleeping and not contributing the load average. However in the case of network filesystems processes may well be in Disk Wait while waiting for the server to respond.