I can't believe P.T.'s/A.T.'s working with elite teams are still prescribing this exercise as a method of reducing hamstring strains & preventing ACL trauma. It's tunnel vision focusing on the sarcomeres of the four muscles themselves. What about improving neural drive? Isn't that part of strength & power output too? Who ever strained one with the leg posterior to the torso? There is no carry over what so ever of this exercise to upright function.
My opinion is the resurgance of this exercise has something to do with the resurgance of isokinetics in the literature. Trying to find an "on field" way to replicate it. I'm seeing a lot of "quad-to-hamstring strength ratio" and "bilateral discrepency" terminology that I heard back in the early 80's.
There's some talk of the pelvis' role in the injury process, but they feel the the hamstrings are influencing the pelvis, rather than the other way around, as I see it on the high school level.