The Ontario Cereal Crop Committee conducts cereal crop performance trials annually, providing a rigorous basis for variety testing and farmer recommendations. This data holds valuable information to be mined for insight. Historical winter wheat trial data between 1971 and 2018 was analyzed to (i) quantify genetic, agronomic, and overall progress in yield gain for winter wheat; (ii) compare the predictability of variety estimates for subsequent years based on single year or multiyear evaluations; and (iii) assess the potential of genomic prediction using molecular markers applied to trial entries. Genetics contributions to trial yield have been linear, yet overall yield gains are stagnating because of yield reductions due to non-genetic effects. Multiple-year trials and single year trials have similar predictive powers. Genomic prediction of yield has a high accuracy of 0.65. Markers predict yield because of kinship rather than because of linkage to causative QTL.