This research investigates the multiplicity of explanations offered by classical morphologists for anomalous morphological forms arising from irregular metathesis and substitution among weak letters. The study highlights how scholars differed in accounting for such irregularities, a divergence rooted in varying criteria for phonetic lightness, unequal familiarity with dialectal variants, and differences in the extent to which attested usage confirmed whether a root appeared with waw or ya’ in a given pattern. Some morphologists inferred unattested forms through logical permutations of the root, while others justified anomalies through semantic grounds or by appealing to the speaker’s psychological state, including illusion or poetic necessity. Structured into two main sections—one on anomalous metathesis and the other on anomalous substitution—the paper analyzes the types and motivations of these justifications. The findings show that the plurality of explanations reflects differing interpretations of articulatory processes aimed at ease of pronunciation, a relative and acquired feature shaped by tribal linguistic habits. Moreover, the uneven distribution of transmitted evidence across dialects played a key role in producing divergent justifications for the same irregular forms.