Just to be clear I am not saying there is something evil about low bar squats. I DO low bar squats. As well as high bar. There is just no sense, however, in people running around telling everyone they need to "switch" to low bar. It's just silly.
There your three basic basic postions. They are kept at the same height for illustration purpose but you imagine that is the same guy doing all three. All that has changed is what has to happen to get the bar in the center of gravity or whatever. The line down the middle tells you everything.
Anything else is done ON PURPOSE. It is an intentional alteration and it has nothing to do with "correct" or "optimal" or any of that. At least as for as "strength" is concerned. As far as numbers...powerlifters do what they need to do to get the biggest numbers. I know there is a lot of "marketing" out there saying otherwise.
BTW, we mentioned EC..the guy is a record setting powerlifter. He straddles both worlds. As a "performance enhancement coach" which is sort of the new term of strength and conditioning coach, lol AND as a powerlifter. He doesn't have all his people doing low bar squats. WTF? You mean just because he's a powerlifter doesn't mean he has everybody become his clone?! How can that be. Fact is the guy hardly uses back squats at all.