Why is AOC contributing to Blue Dog incumbents?

The Guardian poses this very good question. The stated mission of her PAC, Courage to Change, follows. So what's up with this AOC?

“Contributions will be used to make early investments in progressive challengers that can even the playing field against established incumbents, and bolster progressive leaders in Congress who take difficult but righteous stands. All endorsees will embody the ideals of racial, social, economic, and environmental justice. Courage to Change will refuse all corporate PAC donations, as will our candidates.”