Throwers are big individuals. Although having size helps make throwers throw further due to more muscle mass and longer levers, throwers often struggle to move as quickly and can't hit as deep of range of motion as other athletes. This is due to a lack of mobility. Larger size almost always comes with tighter joints. By improving mobility, throwers can take more advantage of the strength that they have by being able to be accelerate at deeper ranges of motion adding speed to the throw and power to the finish.
Mobility as a term is different than "flexibility". Being flexible means that an athlete can passively reach deep ranges of motion. However, mobility is when the athlete has active stability in that position with the ability to move out of that position with control. Although having passive flexibility is very important, having mobility takes it to the next level.
Ankle mobility is crucial to improving the throw as there is active dorsiflexion and plantar flexion that occurs. In the spin, throwers need to keep their heels high off the ground, or plantar flex with the left foot out of the back and the right foot through the middle of the circle. Being able to dorsiflex, or bring the toes up towards the shin, is crucial when squatting to be able to hit depth in the hole.
PVC Pipe Walks
Build proprioception through the feet while developing stability in the ankles. Walk on the PCV pipe rolling it forward for 15 meters.