Why is HEDIS so hard for many organizations?

Why is HEDIS so hard for many organizations?
I think many companies are having a rough time coping to the changes in the market.  Change is slow especially in Health Care and with Affordable Care Act passing a few years back changes hit the market at lightning speed(for Health Care).  Everybody knew it was coming but I don't think companies understood how important HEDIS was to become. These numbers are now how many HMO's live and die by.  So much emphasis has been put on these by HHS and CMS that now all companies talk about is this and how to make numbers better.  The problem is there is no easy silver bullet to good HEDIS numbers.  A lot of HMO I think shot themselves in the foot when they scaled by on outreach services in order to cut costs. Then they turned around and dumped the responsibility onto the provider practice to move the scores.  While it made sense in the short term for costs in the long run it will cost them.  You won't be able to move those numbers and get better ratings unless you invest in outreach and analytics.  You need to attack the problem from multiple angles of intervention and have different programs based on your populations.