If the president (Shanahan) did indeed step inn (by all accounts often enough) to block trades and moves made by the GM (Dubas) in what universe is it fair to blame the GM for any of the teams problems ? Dubas was Shanahan's hand picked hire, not only was he responsible for bringing Dubas on board but also for directly limiting Dubas's ability /freedom to do the job.
If the GM is only allowed to make the moves the president OK's then what really is the point of having a GM in the first place ? Simply put , the bad moves Dubas made are just as much on Shanahan, one could even say even more so, on him as they are on Dubas. As someone living in Ottawa who follows the Sens I am well aware of the all but negative impact such scenarios and ones with strong similarities tend to have on the team/organization. Maybe its just pure coincidence but after the Sens owner passed away (RIP) the Sens GM appeared to become far more capable at his position. Its worth mentioning because the owner for whatever reason choose to stick his nose into and get involved in matters of which neither required his involvement.
Don't think there has ever been a cup winning GM in the NHL who had someone breathing down their neck and limited freedom to do the job they were hired for. This is not a case of who has say over who. The president can have his say, but to do it often in a way that is preventing someone you hired for that job reeks of mistrust and lack or structure. The GM position is one that should come with full control and freedom in all aspects related to the GM position.