In a revealing column written for sport website The Roar, Rathbone described White as a ''highly strung, emotional and complex individual'' who was ''always chasing the next opportunity''.

Rathbone and White have a long association, dating back to winning a Junior World Cup together with South Africa in 2002 as captain and coach. It was White who convinced Rathbone to come out of rugby retirement and play for the Brumbies this season.

But Rathbone said he was perplexed by White's decision to quit the Brumbies.

White has cited family reasons in South Africa and missing out on the Australian head coaching role to Ewen McKenzie as reasons behind his release from the Brumbies. But Rathbone has questioned the motives behind White's sudden exit.

''For all Jake's success, he appears unsatisfied, always chasing the next opportunity. And so it was when he applied for the Wallaby coaching position,'' Rathbone wrote.

''I know how disappointed Jake was at missing out on the Wallabies job. I know he felt as though the politics that marred his time with the Springboks and which he believed he had escaped in Australia had burnt him once more.

''With that said, failure to secure the Wallabies job is not an acceptable reason to resign from the Brumbies. It's not even close to being an acceptable reason.

''If Jake made his decision for family reasons, it's an entirely different matter. No reasonable person would stand in the way of somebody with a desire to be closer to loved ones.

''I hope that this is the sole reason for Jake's decision. But if pining for home and family is Jake's rationale for reallocation [sic], why apply for the Wallaby coaching job?

Rathbone was in England when he received the text announcing White's departure from Canberra.

Brumbies players were widely shocked by the decision, although White dined with members of the Brumbies and Australian Wallabies squad in Cape Town on Wednesday.

Rathbone gave deep insight into White's complexities as a coach.

''His complete faith in his program borders on the delusional, and yet he seems to have an uncanny knack of willing his vision into a reality.

''Jake understands the factors which underpin success in team sports as well as anyone.

''He ensures that he surrounds himself with the very best personnel. He pays attention to standards and details and he always maintains the infectious conviction that his program will produce success.

He is usually right.

''At the same time, I've come to know Jake as a highly strung, emotional and complex individual who can get bogged down and consumed by irrelevant issues and peripheral details.''

While he questioned White's exit, Rathbone also praised his long-time mentor for reviving the Brumbies program and leaving it in a position for ongoing success. Rathbone said White had set ''unprecedented levels of professionalism''.

''Ultimately, no team wants a coach who is not fully committed and passionate about achieving team goals, which is why Jake's decision appears to be in the best interests of both he and the Brumbies.

''What Jake and his support staff have created at the Brumbies is remarkable.

''As a result, the current generation of Brumbies are indebted to Jake for creating the best rugby program in Australia.

''In [assistant coaches] Laurie Fisher and Stephen Larkham, the Brumbies have two utterly selfless individuals to carry the team forward.

''Both Laurie and Bernie will always put the team first and have long been doing the bulk of the hands-on coaching. In this sense, the Brumbies are well-positioned to transition into next season in good hands.''