I think the Chargers prove that you can have alot of talent, but if your coaching sucks, then your team is going to suck.
Pioli could easily get full GM control of another team, but without the scouting/coaching in place, he won't end up producing a super bowl contender.
Pioli, among avid patriots fans, is greatly appreciated. Pioli, among casual fans, is unknown. And I could see how that can potentially irk a person & make them want to go elsewhere.
The problem is that, like BB, other top coaches have full or partial GM control. So, I don't think Pioli is going to find a situation where he's got a top coaching staff, and is able to receive full GM control.
I hope he stays, because I think BB/Pioli make a great team. I won't fault him for leaving. I just don't think the sun is shining brightly on his destination city. And hopefully for him, to receive partial credit for building one of the great dynasties is more appealing than receiving full credit for building an average franchise.