Hamstrings...to stretch or activate

As I have been doing my internship I have learned from one coach that follows a physical therapist much that the hamstrings are normally at an optimal performance length. Meaning that they should not be stretched but only activated. This is what I have come across:

1. Hip misalignment due to extremely strong hip flexors, inactive left adductor, inactive right glute
2. 90 percent or more of individuals are right leg dominate
3. Strong hip flexors tend to imbalance the hip's position due to origin and insertion, which means the hamstrings are normally at an optimal length.

What do you all think?

Here at Nebraska we have baseball perform two realignment exercises pre and post lifting session to restore hip alignment. If anyone is interested in this, know a website which may be of interest.