An augmented reduced mechanism (ARM) for methane oxidation, consisting of 16 species and 12 lumped reaction steps, was developed from GRI-Mech 1.2. It showed excellent performance in reproducing the global response of a wide varieties of combustion phenomena including auto-ignition, laminar flame propagation, and counterflowing non-premixed systems under extensive thermodynamical parametric variations including those of temperature, pressure, and composition. The present study extends the rigor of validation of this reduced mechanism to the next level by showing that good reproduction still exists for the detailed evolutionary and spatial structures of these phenomena. Validation comparisons have also been conducted for the two skeletal mechanisms developed by Kazakov and Frenklach, showing that DRM-22, which consists of 23 species and 102 elementary steps, appears to be the minimum size for a skeletal mechanism to approach the comprehensiveness of the 12-step ARM.