It really is baffling to see Newcastle fans, even the odd logical one, refusing to attach any blame to Rafa. You correctly point out that Dick and PDC were in very similar positions to that of Rafa and they both did far better and achieved the objective of staying in the PL. Also, they did so with a squad that didn't have 80m spent on it. Without the game in hand Rafa had too.
Looking at just the facts (prior CV, relegation challenges, outcome) Rafa is more like Felix/Fulham than Dick/ Sunderland.