I think I see what you are getting at, in that the mutations that initiate each evolutionary step are random, but selection is not random. It is not a coincidence that Impalas and Cheetahs can run at about the same speed, and it is not a coincidence that Pronghorns can run as if they were prey for Cheetahs, as until relatively recently, they were. This does not mean that every coincidence in biology has an evolutionary origin.
That's true... it's impossible to say what's a coincidence and what's not with respect to a given predator/prey relationship. Usually you see a pretty fair match up though. I always think it's interesting when you see a species that is seemingly over-engineered for the purposes of hunting or staying alive:
