I'm not saying who is QB doesn't matter, but because it matters doesn't mean Garrett is the one that pushed Dak on the team. He obviously had to be part of it, but, again, it was likely a collective decision.
The difference between now and 2015 is that we aren't going with the backup QB because the starter went down. We have the chosen starter in place, and are losing anyway. Of course if they lose with Dak, and Garrett gets fired, Dak's downfall will be tied to Garrett's downfall, but that will be because of the losing, not because it proves Garrett pushed Dak on the team.