In block copolymer lithography, subtle distortions in the self-assembled domains, such as tilting or bending, have a strong impact on the quality of the lithographic features upon pattern transfer. We compared the feature size distribution observed at the top-surface of block copolymer thin films with the size distribution that the self-assembled structures project at the substrate interface, i.e., the lithographic image. We performed the comparison for films of perpendicularly oriented cylindrical block copolymer domains with various degrees of lateral order. We found that the size distribution of the projected image does not mimic the well-known Gaussian distribution observed at the top surface. Instead, the lithographic features display a skewed distribution with a long tail toward smaller feature dimensions, a shift of the median and a reduced number of transferred features. The distortions are more pronounced for films with shorter correlation lengths. We propose a simplified model that explains the observed shifts in the size distribution of the projected image by considering the tilting that cylinders undergo in the vicinity of dislocations. The presence of defects disrupting the in-plane orientational order riot only impacts the size distribution of the self-assembled features, but also induces nearby cylinder tilting and some general loss of out-of-plane translational order which, upon pattern transfer, is responsible for the observed distortions on the feature size distribution,