Identify the issue:
The mechanic doesn't offer real value, due to disrupt/buggy cast times.
Understanding the issue:
Atm it doesn't make sense to actually play the class in a hybrid way, because the benefits are not there. Due to high disrupt values healing centered AM/Shaman can't use lifeleech/damage in a reliable/efficient way.
Resolving the issue
The mechanic should award boni to intelligence/willpower calculated from your current stats. If you have e.g 800 Willpower, you should get 20% of that stat per mechanics point towards intelligence, and the other way round. It would reward playing the class in the way it was originally designed.