You say we have given the manager a hodge-podge of inexperienced and 'mediocre' defenders then blame the manager for not magically making them a tight unit?
It is individual errors over and over again that have cost us. Sage has been deprived of Riad and Tomiyasu and Disasi, all three of whom would have been starters in most matches. I don't know if any manager can make this defence work consistently without Riad and Tomiyasu. I do know Disasi has been given little time to bed in and the new players of Anahor and Khalaili need more time.
I suspect time will fix the issue. It's not about giving the manager time, it's about giving the players time.