There is no indication of what size of employer were included in this study.
It's all very well being "academic" about the right thing to do from an ivory tower, but in a jam you will focus on high performers to get you through the crisis, failure to do which will mean that there will be no employees with business-critical skills to worry about anyway.
I suspect that from what has been said in the article that the organisations are pretty sizeable in order to be able to carry some of the overhead attached to the employee engagement.
I wonder what WW would have said about RBS in its former existence with all its Human Capital indicators set to "all employees engaged -all systems go"?
Even great reward packages and communications for all won't save a flawed business model, indifferent product or a management that has insufficient experience.