To evaluate how good corn and soybean yields were in 2015, farmers and agronomists compare their yields to those obtained in previous years. To answer why yields were higher or lower than past years, they develop hypotheses to explain factors that limited yields based on their own experiences, anecdotal evidence from neighbors, knowledge of crop growth and development, and weather patterns. As a next step to the in-season Yield Forecast Project, we can provide an alternative analysis and a yield gap analysis of the 2015 growing season by using the explanatory power that a cropping systems model offers. Our analysis is focused on corn and soybean cropping systems used in the Yield Forecast Project (more information on the cropping systems and the Yield Forecast Project can be found in the June 17thICM News article). In total, we evaluated eight cropping systems; two locations, two crops, two planting dates.