"It is a big job"

In justifying the $188,000 per year that newly appointed Workplace Safety Insurance Board Chair Elizabeth Witmer will earn, Dalton McGuinty said:

It is a big job

And it probably is. It's an important agency. The job might well be worth what Witmer will earn and she might well earn every penny. But that does raise a question: if the job is that big, why was the current chair only working on a part-time basis?
Wouldn't that suggest that the WSIB was being poorly served until this current appointment?