Unfortunately, the difference between 10th and 20th does matter. Not because the quality of education is different, but because the rankings are so self-reinforcing. It's totally circular.
Why is school X ranked highly? Because smart people choose to go there. Why do smart people choose to go there? Because it's ranked highly.
A school that changes in rank gets a different set of applicants, and that changes its reputation without its actual educational quality changing at all.