The 2.5 metric is not to the QB but just when they are past the OL. Would be closer to 2.7, 2.8 or so to the QB
Fields is slow to process this is a fact of who he is and what he has done for 3 years, and he is also one of the longest at holding the ball, again he has done this his whole career
No it depends on how close the OL and defender are to the QB. Again it is arbitrary because differ offenses have different timing as to how long an OL needs to block based on the depth of the routes.
The fact Fields is slow to process doesnt change the fact those players sucked this year. PFF already has data that assigns pressures to the OL vs the QB and so again their grades already take into account if a sack or pressure was the QBs fault.
PFF deemed Fields responsible for 17.6% of his pressures. That is 9th highest in the league but lower than Hurts, Mahomes, Jackson and Allen who are at 22.2, 21.5, 21, and 20.4 respectively. So the reality is that even the best mobile QBs tend to give up more pressures because they all have a tendency to want to hold the ball looking for bigger players. There is nothing unusual about Fields rate of causing his own pressures.
So the point is once you remove pressures that were Fields fault, those vet players still sucked at their jobs. There is no way to blame that on Fields. So stop being biased. Those guys are grown men responsible for their own failures. Stop trying to scapegoat Fields for everything.