It might. But look at this picture. All background is in focus but not subject.
The subject is large enough for AF to catch it. It is not acceptable for me. I can't screw up shots like that.
I have got EF 24-70/2.8L lens quite ago tested it for back/front focus and it seemed to be OK at that time. The camera has no back/front focus problem. It was recalibrated by Canon before.
The problem started showing up in real life shooting situations. The lens was missfocusing mostly at 24-35...