Using Vermiel for an example I think the addition of Martz was a crucial part of things falling into place for a couple reasons...
First off, Martz looked at the film of Banks and told Vermiel they'd all be fired if they didn't upgrade. The moves that happened to acquire better players, who turned out to be key players, grew out of that OC hire.
Second, Martz is a great teacher of offensive concepts. Everyone was dazzled by his scheme, but it was not the scheme that set him apart from most other coordinators. It was his ability to teach that offense an immense playbook install in one camp and have everyone know it cold. That was not the players. That was the coaching. With the OCs the Rams have had that same collection of talent probably would have struggled to be on the same page and the bitching and moaning would start along with turnovers and Vermiel would have been fired most likely.
The point of course is that coaches matter. It is not just about the players. In fact it is very rare to see a player who is so good that he'll excel no matter who coaches him. Gurley is an obvious example, where he could play in a run or pass heavy concept offense with smooth transition. But the rest of the guys on offense need to be well versed so they'll be able to play fast and not be slowed by needing to think and being confused on responsibilities. It's early but Boras seems to understand that. And if he does get this same bunch of guys to know his offense cold they're gonna play fast and people are gonna be shocked by how much better they are.