This study the explores the need to examine the increasingly varied methods of quantifying morphological complexity in regards to their ability to influence structural borrowing across languages, with particular attention to the distinction between enumerative complexity (enumeration of all of the morphemes and distinctions in a system) and integrative complexity (entropy-based calculation of the class distinctions of the system). While existing models in contact linguistics often assume that structurally simpler languages are more likely to serve as sources of grammatical transfer, such accounts typically rely on enumerative measures of complexity alone and do not fully account for the role of irregularity and predictability within morphological systems, quantified by more recent discussions of integrative complexity as compared to enumerative complexity. This study argues that incorporating integrative complexity provides a more comprehensive framework for understanding structural borrowing. Focusing on the Ottoman-Bulgarian contact context, this study compares Old Church Slavonic, modern Bulgarian, and Ottoman Turkish using corpus-based computational measures derived from Universal Dependencies treebanks. Various metrics are employed to measure, calculate, and compare complexity across multiple randomized samples. The results reveal a consistent tradeoff between lemma-to-form expansion and lexical diversity across the languages examined. Old Church Slavonic exhibits high levels of lemma-to-form expansion alongside lower lemma diversity, reflecting a system in which morphological variation is concentrated within inflectional paradigms. In contrast, modern Bulgarian shows reduced expansion and higher lemma diversity, indicating a redistribution of variation across lexical items. Ottoman Turkish occupies an intermediate position, combining relatively high surface-form diversity with moderate levels of lemma expansion. These findings suggest that morphological complexity is multidimensional and cannot be fully captured by enumerative measures alone. By distinguishing between different ways in which variation is structured within a language, this study provides a more nuanced account of morphological organization and offers new insight into how structural factors may shape outcomes in language contact. More broadly, the results highlight the value of corpus-based approaches in refining theoretical models of morphological complexity and transfer.