Establishing exactly what physical elements are needed or require improvement for performing Adage can be slightly misleading and, at times, awkward for the body to perform.
Again this is a discussion regarding active range of motion and passive motion... I still see regular static stretching in order to increase active mobility. And although this works to a point through acutely increasing muscle length, it is a process that requires a significant amount of time, does not create long lasting changes to muscle length and, prior to performance, has been shown to decrease muscle capacity and force output.
A long side having good agonist muscle strength to move a limb through a large active range of motion, there also needs to be a willingness of the antagonist muscle to lengthen in order to decrease restriction in opposition to an agonist muscle action.
Myo-fascial release has been touched on many times before. Considering that a large element to Dance is requires the ability to create positions and lines in order to demonstrate and perform the art, it seems appropriate that we can use myo-fascial release to allow the body to maintain and move into these positions through minimising restrictions in the deep and superficial fascia layers.
The video below is a simple process of Test ReTest and myo-fascial release for the glute area coupled with Active Hip and Knee Flexion.
These principles are employed from Mobility WOD and adapted with reference to Ballet.