NASA's Van Allen Probes observed significant, long‐lived fluxes of inner belt electrons up to ∼1 MeV after geomagnetic storms in March and June 2015. Reanalysis of Magnetic Electron Ion Spectrometer (MagEIS) data with improved background correction showed a clearer picture of the relativistic electron population that persisted through 2016 and into 2017 above the Fennell et al. (2015, https://doi.org/10.1002/2014gl062874) limit. The intensity and duration of these enhancements allow estimation of decay timescales for comparison with simulated decay rates and theoretical lifetimes. We compare decay timescales from these data and DREAM3D simulations based on them using geomagnetic activity‐dependent pitch angle diffusion coefficients derived from plasmapause‐indexed wave data (Malaspina et al., 2016, https://doi.org/10.1002/2016gl069982, 2018, https://doi.org/10.1029/2018gl078564) and phase space densities derived from MagEIS observations. Simulated decay rates match observed decay rates more closely than the theoretical lifetime due to significantly nonequilibrium pitch angle distributions in simulation and data. We conclude that nonequilibrium effects, rather than a missing diffusion or loss process, account for observed short decay rates. Plain Language Summary Earth's radiation belts are influenced by a wide variety of source and loss processes, so it is difficult to model and forecast its evolution or predict its effects on spaceborne assets. Decay timescales for loss processes are essential to understanding this balance, but the theoretical predictions for these timescales in the inner radiation belt can exceed the observed decay times by an order of magnitude or more. We have observed and simulated an exceptional period of radiation belt injection and decay to understand this discrepancy. We have found that changes in the wave properties due to geomagnetic activity can account for the difference: changes in the equilibrium distribution associated with the wave environment result in consistent refilling of non‐equilibrium modes that decay much faster than the equilibrium mode. Key Points DREAM3D simulations of Earth's inner electron belt, based on Van Allen Probes observations, are carried out to evaluate model decay rates Pitch angle diffusion using coefficients reflecting geomagnetic activity demonstrates realistic decay rates Decay rates extracted with a Random Sample Consensus‐based algorithm from modeled and observed fluxes agree, while theoretical lifetimes are too long