Saban has addressed this many times. In phase is a bit more specific than close to the receiver, and has to do with hand placement, running in step, etc. When you consider both back shoulder throws as well, the only way to defend is to either go straight zone or look at the receiver.
The PI is a quality of official thing. As things have deteriorated, the rule has become, "if the defender is not standing with his back to the receiver, all contact is defensive PI". This was clearly indicated at Miami where the receiver obviously initiated contact, was the only one with his hands on anyone, and the DB was called for PI.
That isn't correctable by coaching technique. That is only correctable by getting better officials, which as much as we want, is not likely going to happen.
This is just my opinion, but my belief is that Saban and the coaches know and have made a business decision. They understand that we are going to get called for PI if the defender is slow to turn around. They have decided that they would rather force contested catches and they believe that in the long run, our athletes are better and we will win more often than losing. I also believe that history has proven them right.