We carried out high-throughput computational screening to compare 222 Fe and Ru catalysts for modification of polyolefins via C-H functionalization. Using propane as a model compound for the radical rebound hydroxylation to form isopropanol, we identified strong sensitivity to spin state in the relative behavior of Fe and Ru catalysts. Ru catalysts had greater favorability for metal-oxo formation and isopropanol release over Fe catalysts, a trend that was more significant for higher-spin states. In contrast, Fe catalysts exhibited more favorable HAT energetics than Ru catalysts, with this disparity remaining consistent across varying spin states. These spin-state dependent trends made it challenging to identify a single global LFER, and we instead observed strong sensitivity to how well an LFER held within a fixed spin state. Overall qualitative LFER trends by metal nevertheless suggested that Ru catalysts adhere more strongly to a classic metal-oxo formation vs. HAT LFER in comparison to Fe where the LFER can be readily disrupted.