Observe two vertical dashed lines. They reveal how far the BA Optimizer was allowed to process. At the base of these lines is a label that reports information on what was optimized: "BA Optimized XXX boxes: from [some condition] to [some condition]" (a,b,c)
Boxes within the optimized region are illuminated in a lighter hue (observe the greens are lighter in the above graph), and those outside are drawn in a darker shade, illustrating that they were not "seen" by the optimizer. In effect, this lets you see how the BA buys and sells perform in the "future", without having to wait so many days to pass.
Refer to this page for more information on this topic!