Our HAT BEP slope of 0.30 also contrasts with the widely reported slope closer to 1. However, most prior studies showing strong HAT BEP relations focus only on the a-radical transfer for HAT. In addition to a small dataset, which is more sensitive to noise, we believe that the inclusion of b-radical transfer pathways for the Fe catalysts also disrupts the BEP significantly, as demonstrated in previous studies. Taken together, the moderate correlation between HAT kinetics and reaction energetics and the strong correlation between metal-oxo formation kinetics and reaction energetics suggest that evaluation of kinetics is less important for finding optimal Fe/Ru C-H activation catalysts in comparison to systems where BEPs hold less strongly. Generalizing from our study, because Fe catalysts have more favorable HAT energetics than Ru catalysts, the discovery of Fe catalysts that outperform Ru catalysts in C-H activation would only involve identifying candidates with lower metal-oxo formation energies. This is more feasible with Fe catalysts because minimizing metal-oxo formation energies may not result in an energetic penalty for HAT due to weaker scaling relations in Fe. While finding better-performing Ru catalysts would only involve identifying candidates with lower HAT energies, this would prove challenging without compromising the favorability in metal-oxo formation because Ru catalysts are more constrained by the scaling relations. Overall, our comparison of Fe and Ru catalysts over a wider chemical space reveals the overlooked potential of earth-abundant Fe catalysts in polyolefin functionalization with better tunability in C-H activation reactivity.