I don't think it is that hard. Players that use an open stance with the long clubs have been predisposed to chronic back problems: Trevino, Zinger, Couples, Nicklaus.
Players with a reverse-C, or who otherwise block the hips through impact, have also been predisposed to chronic lower back problems: Gulbis, Nicklaus again, Monty, Greg Norman, Love, Middlecoff, Carol Mann.
Academic research concluded that the incidence of lower back problems increased after the introduction of the "x-factor" theory (thanks, Jim!).
Snead, Hogan and Boros had closed stances and did not reverse-C. They played great golf into their 50's.
Two players with terrible backs, Jake and Pooley, changed their swings so their backs didn't hurt anymore and resumed their tour careers.
It's not rocket science or voodoo. It's right there if you're willing to look at it.