A recent experimental study reported the catalytic oxidation of C-H bonds in polyethylene using a homogeneous Ru catalyst that can selectively incorporate carbonyl and hydroxyl functional groups with high turnover numbers. On the contrary, Fe catalysts with proven activity for C-H activation did not demonstrate substantial activity for polyethylene oxidation, which was attributed to the incompatibility of the Fe catalysts with the reagents and reaction conditions. However, this study evaluated only three Fe catalysts due to the practical constraints associated with extensive experimental screening. Thus, it could not definitively confirm the inactivity of Fe catalysts relative to Ru catalysts for C-H oxidation of polyolefins. Given the ubiquity of C-H activation catalysts containing the relatively earth-abundant Fe as the metal center, calculations are well suited to facilitate screening over larger numbers of Fe and Ru catalysts and could provide a more comprehensive comparison of their polyolefin oxidation activities. Indeed, high-throughput screening, guided by density functional theory (DFT) calculations, has facilitated the evaluation of catalyst activity for C-H activation across diverse, large design spaces. The computational cost of DFT-based screening is often lowered by scaling relations, such as Brønsted-Evans-Polanyi (BEP) relationships between activation and reaction energies and linear free-energy relationships (LFERs) between distinct thermodynamic steps, that draw linear correlations between DFT-computed descriptors and reaction parameters. For example, ligand field strength has been shown to correlate with C-H activation reactivity of Fe catalysts. These scaling relations, however, are readily disrupted by varying metal identities, oxidation, and spin states in open-shell transition metal catalysts. Additionally, scaling relations have also been shown to be altered or broken by changes to metal-local structure or non-covalent interactions that can influence the stability of certain reaction intermediates over others. When searching over a large set of Fe and Ru catalysts to identify promising candidates for polyolefin C-H oxidation, it is important to examine the applicability of scaling relations to ascertain whether manipulation of ligand field strength is a valid strategy to tune C-H activation reactivity in Ru catalysts.