1. A method performed by a computing device, the method comprising: obtaining events from an event log, the events reflecting failures by a plurality of network devices; filtering the events using one or more criteria to obtain a sub-set of the events; evaluating traffic flows through the plurality of network devices to identify specific network devices that carry application traffic for an application, the specific network devices being included within a network stamp of the application and including a group of redundantly-configured network devices; characterizing network device service levels of the specific network devices included in the network stamp using the sub-set of the events; characterizing an application service level of the application based on the network device service levels of the specific network devices in the network stamp of the application; and outputting the application service level via an output device of the computing device.