Since When Did First Time HCs Have a Say in Finding a GM Become a Trend?

It's been a thing and it generally happens in situations where a team is seeking a new HC and GM. As I mentioned in another thread, just as coaches talk to one another about the possibility of working together, so do coaches and GMs. So, GMs tend to have candidates that they want to work with--sometimes a particular one rather than a set of candidates and the same is true for coaches who often want to work with certain front office personnel with whom they see themselves in alignment. It makes sense. Both the GM and the coach want to make sure they can work together.

But it is rare that a HC will go in and demand or request that a GM is fired or reassigned to another role. If the organization hasn't had recent success, and the coach is very influential, you can see ownership choose defer to a coach over a GM. For example, when Jon Gruden and Reggie McKenzie kept butting heads, the Raiders chose to fire McKenzie. And then Gruden got to hire his guy, which ended up being Mike Mayock with Jon having the final say on personnel decisions. But again, that is rare. In most instances, you get a GM who might come in and have a particular coach he wants to hire. Like Chris Ballard wanted Josh Daniels but had to wait a year. Or Bob Quinn wanted Matty Patricia but had to wait two years. Or even Kwesi Adofo-Mensah wanted Jim Harbaugh though there was push back within the organization and they chose not to offer Jim a contract; instead, O'Connell was eventually hired.

In some cases, an influential or highly-sought-after coach might ask to have final say over personnel decisions if a GM is already in place. For instance, Sean Payton has final say over Denver's roster though he and George have found a way to work together.