Because of the retractable roof and maybe partly the style of roof that was chosen, the structure is very tall...so this would tend to mean the shadows move futher out on the field earlier. Of course, the angle of the sun is a factor too, which means the time of year and the longitude of the location are factors. Finally, the amount of foul territory has an impact on where the shadows fall. I don't think the shadows are a result of any mistake, they are just a consequence of the design. Since there is a roof, it is a tall structure both in terms of the stands and the roof itself. They also wanted the stands to be close to the field. I assume, they wanted to not have an indoor dome feel, hence the large glass areas between the stands and the roof. I think, with the roof closed, it'd feel depressingly like the metrodome had they not put the glass areas in. edit: I want to correct something I had posted, looking at the cub game right now, I realized/rembered that the shadows on the field only come from the 3rd base side as the sun is setting there. Because the structure is so much shorter than MP, the stands on the first base side do not create an shadows that would affect the field. There is a huge difference as it is 3:40 right now and shadows are barely appearing just right along the wall.