This presentation addresses statistical challenges in modeling the deterioration of complex systems, spanning from individual unit degradation to interdependent network failures. First, we introduce statistical degradation data modeling using stochastic processes. Then, we shift to modeling recurrent failures in large-scale infrastructure networks (e.g., water distribution systems). Motivated by 16 years of Scottish Water pipe failure data, we propose the novel Network Gamma-Poisson Autoregressive NHPP (GPAN) model. This two-layer framework captures temporal dynamics via Non-Homogeneous Poisson Processes (NHPPs) with node-specific frailties and spatial dependencies through a gamma-Poisson autoregressive scheme structured by the network's Directed Acyclic Graph (DAG). To overcome computational intractability, a scalable sum-product algorithm based on factor graphs and message passing is developed for efficient inference, enabling application to networks with tens of thousands of nodes. We demonstrate how this approach provides accurate failure predictions, identifies high-risk clusters, and supports operational management and risk assessment. The methodologies presented offer powerful tools for reliability analysis across diverse engineering contexts, from product lifespan prediction to critical infrastructure resilience.