The initial "sharp decline in faith practices" was by the clerics. When they were caught in their generally unchristian, and specifically un-Catholic shenanigans, the populace rightly responded --- trust lost, practices questioned, doctrines ignored. 

The populace then seem to have discovered that life got better. 

The church has only itself to blame.

I applaud the Irish for recognizing evil and taking steps to unburden themselves of it.