Observation of a conversion-dependent enantioselectivity in asymmetric reactions with nonenantiopure catalysts or reagents may be diagnostic of kinetically complex behavior. This paper shows how reaction simulations based on parameters derived from initial enantioselectivity data provide an extension of the Kagan MLn models as powerful mechanistic tools in asymmetric synthesis. This approach is illustrated for an example of a stoichiometric reduction of aralkyl ketones with chiral borane reagents and is also discussed for several cases of catalytic reactions.