He was saying that it was pure coach-speak to talk about bringing in a new O or D co-ordinator and how they were going to run the same scheme and system, blah blah. He said it's not true. There are always differences right down to the footwork a new coach wants. And that it takes some time for the players to adapt and internalize to where it becomes second nature. What formation the DC calls on any given situation is also different.
It has hurt the Rams a lot to have their coaching staff raided with a O or D co-ordinator leaving for a HC job nearly every year. Lots of adjusting has to take place. The good news is that on the O side, McVay is the real OC. But the D side? Different story.
The Rams D will get better as the year goes on. Morris, the new assistants and the players are all learning as they go. The Rams have deep talent on the D and 2 generational superstars. It'll come together even if it takes 6 or 8 games to get there (barring the injury bug of course, to their top guys).