Coaching absolutely matters, I can tell you that. Going from college to NFL is like having your bachelors and going straight to doctorate.
The speed of the game is what is different. There are only so many offenses you can run, only so many guys that need to be blocked. Sure, defenses are more complex and disguised, and coaching helps with that. But at the end of the day, Lucas Patrick didn't go from a piece of shit to the best center in the league from being coached in training camp.
I don't know what went on with those guys last year. Maybe they weren't coached particularly well, but they also would tell you that they have always known how to block, and how to process a defense.