And Saban learned it from Bilichick, who learned it from Bill Parcelles.
But there’s nothing unique to it, ALL coaches used to practice that way. Which is why pretty much any top 10 team from the 80’s would be national champions today. Saban is just an old school coach, nothing special. His way of doing things would have been a dime a dozen back then.
A lot of coaches have gotten away from that with all the spread and air raid football you see today, plus the NCAA and their rules on practicing. And the feeling that you need to coddle this generation in order to recruit. But it used to just be normal to practice physical.