Education director Steve Marshall's resignation has prompted suggestions of frustrations with the job.
A successor for the education director Steve Marshall is already being head-hunted, TES Cymru was told this week. However, many believe that the Aussie's shoes will be big ones to fill when he leaves at the end of March.
Mr Marshall's appointment in January 2006 was a major coup for Wales, and he quickly endeared himself to key education stake-holders.
In his statement, Mr Marshall said his experiences in Wales had been "rich and rewarding".
"I am proud of our successes and pleased we deliver consistently high standards. We will ensure the department continues to be led by a highly capable and expert leadership group," he said.
Tributes to Mr Marshall's first-class work record were made this week. Professor David Egan from the Cardiff School of Education at the University of Wales Institute, Cardiff (UWIC) and former special education adviser to the Assembly government, said Mr Marshall's departure was disappointing but the job offer in Canada had just been too good to turn down.
"Steve has developed strong relationships with all the education stakeholders in Wales," said Professor Egan.
"It was great to get him but he was going to go eventually - he was known across the world as one of the great education reformers."
A joint article by Mr Marshall and Professor Egan, published in the Australian Journal of Education last November, reveals how importantly the school effectiveness programme about to be unleashed in Wales was viewed by the DCELLS director.
"It can be suggested that the absence of a strong school effectiveness movement has contributed greatly to the way in which student performance has, particularly in secondary schools, reached a plateau," it said.
But elsewhere there were suggestions that Mr Marshall's motives for leaving Wales were informed by more than the chance of a plum job - including possible frustration over financial constraints.
The former headteacher had always been keen to stress that countries with the best educational performances were not always the best funded.
But NUT Cymru spokesperson Rhys Williams said: "I just wonder with Mr Marshall if it is frustration at not being able to deliver what one would want because of the financial constraints."
He compared Mr Marshall's departure to that of Wales rugby coaches going back to their native New Zealand. "It is a bit like Graham Henry or Steve Hansen coming to Wales, then leaving shortly afterwards," he said.
Brian Lightman, national president of the Association of School and College Leaders, said: "During his short tenure at DCELLS, Steve Marshall has brought the kind of experience that is so essential to a small country like Wales.
"He leaves before the school effectiveness framework has been implemented. Secondary school leaders will hope his departure will not lead to a loss of momentum in this and other aspects of the Learning Country.
"Perhaps Mr Marshall was unwilling to try to make bricks without straw. School leaders cannot be expected to do this either."
Mr Lightman, head of St Cyres Comprehensive in Penarth, has two of Mr Marshall's teenage children at his school.
Leader, page 28.