A device, method and tangible computer-readable medium are provided for detecting output discrepancies between representations of a block in two system models. For example, a first representation of a block may represent a default configuration and may execute in a first model. A second representation of the block may represent a user-modified configuration for the block and may execute in a second model. The user may execute the first and second models and may compare results using an exemplary embodiment. The embodiment may allow the user to define criteria and weightings for the criteria and to use the criteria for generating objective functions and constraints. The objective functions and constraints may be used to evaluate the performance of the two models. The embodiment may further perform trace back operations with respect to a model to determine a location in the model that produces an output discrepancy.