I don't have her improving from the Guineas at all in her two runs this year. On my ratings her runs this year are exactly the same. Older horse good R75 level and maybe open class competitive. Lengths off Well Written. How do you reach a conclusion that she has improved a lot?
They all have a chance as @Chief Stipe said. Even Black Caviar might have gone amiss in a race. If you can assess that chance more accurately than the bookies, then you can make a profit. That's the fundamental principal behind successful punting.