This definitely seems odd. WRs have underperformed but far from the biggest issue. He would have been at least the 3rd coach that needed to go just on the offensive side of the ball.
It wasn't just this game. They are giving up 78% completion percentage. 29/33 this week. Secondary has sucked for decades. Pass rush was definitely non existent, but you anybody that thinks the secondary has played well isn't being realistic.