I think that they must have transposed the labels. The graph must mean that a student who goes into Harvard leaves an $80,000 a year salary and after two years gets a $115,000 a year salary. That doesn't tell us all that much unless we know how much that same person would be making if he or she stayed in the workforce for those two years.
I find that to be a shocking figure after the 2 years and huge amount of money that people generally invest in getting an MBA.