From a distance, Quinnipiac University’s new national poll looking at the 2020 Democratic primary looks fairly familiar. There’s former vice president Joe Biden atop the field, with a 19-point lead over the next-closest candidate, Sen. Bernie Sanders (I-Vt.).

The rest of the top tier includes familiar names, too: Sen. Elizabeth Warren (Mass.), Sen. Kamala D. Harris (Calif.) and South Bend, Ind., Mayor Pete Buttigieg.

When we look at how the top tier has evolved, though, things get interesting.