Again, what we are talking about here are opinions. I am going to give you a couple of situations and you tell me if/how they fit into what you have said.
These will be two ends of the time spectrum. I can give more if needed:
Situation 1: Let's start with Brownwood in 1960. Prior to 1960, Brownwood had no State Titles. Gordon Wood arrives and in his 1st year they win the Title. This would be his 1st of 7 total. Now, when he left after the 1985 season, Brownwood has not won a State Title. So, insert everything you've said into this situation. What you have suggested as a reason for winning only took place when Gordon Wood was there between the years 1960 and 1985? And none of this happened before and after?
Situation 2: Let's look at a more resent situation. Carthage coached by Scott Surratt. Before Scott arrived, Carthage did not win a State Title. The second year he was there, he won one. This is his 1st of 8 Titles. Now, again, insert what you talked about into this situation. What you have suggested as a reason for winning only took place when Scott Surratt was there between the years 2007 and 2020? And none of this happened before he arrived?
It appears clear to me that the coach made the difference here. Just my opinion. What say you?