I think it's an interesting decision to replace the GM. I think ownership & C-level, president, etc. should let the GM manage the team, but it takes a certain level of knowledge to know when it's actually time to cut them off. When the fans reach fever pitch there's already a mandate, and an 'out' if you will, but it probably shouldn't have to come to that.
No confidence voting systems with a very high threshold are interesting to me here as the GM's subordinates are probably more qualified to assess things than ownership/c-level. They shouldn't be able to elevate anyone, however, so coups are harder.
As for the Oil, if they drafted well, things would probably be going a lot better for them. They'd still be hindered by bad decision making at the top, but they'd have a pipeline.