What are the factors that have led to the slump at Mercedes besides the regulations that they do not seem to ber able to get right after two goes at it?

Two key factors come to mind:-

1. The loss of Nikki Lauda
2. Possible key personnel leaving or defecting to competitors of Mercedes.

For the second point, l wonder if that alone is enough to account for their clear loss of intellectual edge that has seen them lead the grid for many years. They still have the essential core personnel in place. So what else is the issue with Mercedes?