I'm wondering about one thing why do the hamstrings and the calfs get tight in the 1st place? I know this is not your question but wouldn't it be sensible to have ask that question 1st? Muscles won't do a thing unless a nerve is attached to provide a signal. The signal of nerves to the muscle and environment will influence the muscle tension and thus the pull onto the tuber at the pelvis. because of this changes will take place regarding the stability of the pelvis and the spine as a whole. Actually the changes will/can provoke changes in the signal of the nerve and opting the muscle tension even more and so on and so on.
1 Pain is in the brain 2 muscles are dead without the nervous system. 3 By the way most football players have very tight Hamstrings (FMS score 0) but do not have back pain