One way to express realism is that it insists on knowing what before knowing how. Why is that? Because for a realist metaphysics precedes epistemology, which means being precedes knowing. Something is, whether we know it or not.
A question students are asked is, If a tree fell in the forest and no one knew it, would it still have fallen? The realist answers Yes. So if we come upon a tree on the ground in the forest, what happened? We are entitled to investigate how the tree got on the ground after we have ascertained that the tree is on the ground.
This is not obvious to anti-realists, who want to know how something got there before they will agree that it is there. Appearances after all can be deceiving. If we can trace a chain of events that leads from the tree growing up, dying, and then falling on the ground, then we can be sure that there is a tree on the ground. Otherwise, maybe not.
One reason anti-realists are attracted to evolutionary theories is that they (purportedly) tell us how things got here. Now exactly what it is that got here may still be fuzzy. After all, evolutionists haven’t figured out exactly what a species is, but they are certain that whatever a species is, it got here by evolution.
Realists on the other hand want to be confident that something called a species really exists before investigating how a species came to be. Before the 19th century it was widely understood that species were created and so had exactly the properties with which they were endowed by their Creator (to use the phrase of the Declaration of Independence, 1776). This is what motivated early modern science to explore the world the Creator had made.
After Darwin, the certainty about what things really are decreased even as the confidence about how things came to be increased. The identity crisis is an invention of the evolutionary mindset. Meanwhile realists are waiting for anti-realists to figure out who they are so a real dialogue is possible.