In one embodiment, a service maintains a mobility path graph that represents roaming transitions between wireless access points in a network by client devices in the network. The service associates metrics regarding roaming delays to mobility paths in the mobility path graph. The service identifies a roaming boundary change that is predicted to reduce roaming delays between two or more wireless access points in the network, in part by assessing the metrics regarding roaming delays associated with the mobility paths in the mobility path graph. The service provides an indication of the identified roaming boundary change to a user interface.