The size of the curds determines how much white space and how much blue there is in a blue cheese. What makes blue cheese blue? Cultures that change milk to cheese, and air. The "dots" in this cheese are made from jabbing the "white" young cheese with needles - this lets air inside the cheese that the blue mold needs to grow.
See the variety of curd sizes? The blue will grow in the spaces between curds. 
The cragginess of the individual curds and the holes between them creates air spaces for blue mold to grow. Without the air spaces there would be no veining in the finished product - just stab marks.
After aging, the large interior air pockets become blue patches, the spaces between curds become veins. It takes at least 60 days to get from white curds to blue cheese.