Firing someone every time they make a mistake is hardly a productive means of growth for any business, F1 design included.
The best way to improve is to first fail and, as this is possibly (hard to prove/disprove given the woeful Honda engines in the back of them) the first bad McLaren chassis he has been involved in, you hope he has learned from the mistakes of 2018 to improve going forward.
PP and his aero team have had some pioneering concepts and ideas that the whole grid have ended up adopting, even whilst they’ve been lingering at the back of the field. Fingers crossed they can translate that creativity into to a more stable and competitive MCL34.