Haven't encountered it changing. Different but similar question for you: which is more important, overall rating or creating a team that plays the same playing style?
I have had both senario's. My staff have the same style and close in the formations however the team has a varied mix and so long as the squad is young enough and in fitness form then you shouldnt have a problem.
The trick i find is that the Staff have to be set right and so long as you have depth in squad memebrs then youll do good.