I use this exercise to improve functional upward rotation of the scapula above 90 degrees of flexion. This minimizes rhomboid and levator activation that is more prevalent with traditional shrugs.
Brian reveals an excellent way to unlock a tight ankle and soleus with this exercise. Focus on letting the front knee move in line with the foot but over the toes toward the wall. The rear foot heel can come up but the front heel should stay on the ground.
I use this exercise to promote increased hip rotation (mobility) on the moving side and stability on the stance leg. You may opt to use upper extremity support initially and then once you master control and form, do it with no upper body support.