With current techniques, traffic monitoring and control is a data intensive process. Network control on a higher level, using high level variables, can make this process less data demanding. The macroscopic fundamental diagram relates accumulation, i.e. the number of vehicles in an area, to the network performance, but only holds for situations with homogeneous congestion. This paper shows that subnetwork accumulation and the variation thereof are also good precursors of the network performance. With this result, traffic control can be performed with less data, namely only the accumulation of the subnetworks rather than all speeds and densities for the whole network.