An article of footwear includes an upper and a sole assembly secured to the upper. The sole assembly has a shell having a first hardness and a recess. A lateral side of the recess has a first depth and a medial side of the recess has a second depth that is different than the first depth. A first aperture extends through a forefoot portion of the shell, with the first aperture defining a first tongue fixed on a medial side thereof with a remainder of the first tongue free to flex with respect to the shell. An insert has a second hardness and is seated in the recess. A lateral side of the insert has a first height and a medial side of the insert has a second height that is different than the first height, with the second hardness being different than the first hardness.