I thought this was a very interesting reflection by bret Contreras on the issue of pelvic tilting in certain exercises
Click here
the only thing id add is that i feel the  Mcgill and Verkoshansky V  Mel Siff . is   a bit contrived. I think they deal with different types of people with different out puts.
“The pelvis plays a vital role in the ability of the athlete to produce strength efficiently and safely, because it is the major link between the spinal column and the lower extremities… a neutral pelvic tilt offers the least stressful position for sitting, standing and walking. It is only when a load (or bodymass) is lifted or resisted that other types of pelvic tilt become necessary. Even then, only sufficient tilt is used to prevent excessive spinal flexion or extension… The posterior pelvic tilt is the appropriate pelvic rotation for sit-ups or lifting objects above waist level. Conversely… the anterior pelvic tilt is the correct pelvic rotation for squatting [and] lifting heavy loads off the floor. – Supertraining 2009 (Hat tip to Pavel Tsatsouline for finding this quote)”
Bret believes this: “I’ve learned much of my spinal biomechanics knowledge from Stu and highly respect him. In this case, I feel that some slight pelvic tilt can help buttress the spine by creating torque in the necessary direction in order to help stabilize the spine and prevent buckling. However, the pelvic tilt isn’t to end-range so it doesn’t dramatically impact spinal posture, but rather keeps it in check”
The difference in the opinion is probably a matter of perspective  and  objective. McGills observation ( and I’m a Mcgill fan) is that bad backs are correlated with poor back control and use. back pain is the result of years of systematic abuse. His battle is to get clients to learn or relearn back positions.
Verkoshansky and Mel Siff are not trying to cure your bad back, they are trying to get you to lift more. For  advanced athletes who do not suffer back pain, their approach is great.
For people who do suffer back pain, getting an effective general purpose  healthy motor pattern is far more important.