The approach to Umaga, seen as a Super Rugby head coach-in-waiting but one who has been happy to bide his time at ITM Cup level with Counties Manukau, is the proposal CEO Michael Redman has been working on but has been unable to talk about publicly. Redman could not be reached for comment.
If Umaga accepts Redman's offer - and the longer he waits, the more his value rises - he is likely to come on board as the backs coach for a season before taking over Kirwan's role as head coach for 2017 onwards.
It is effectively the role which Crusaders assistant Tabai Matson turned down after controversially visiting the Blues' HQ last month.
It is understood that the presentation in April of Kirwan's succession plan regarding Matson helped turn board members Bolton, Laurie Margrain and John Morgan to the struggling coach's way of thinking. Before that they were aligned with Auckland representatives Brian Wilsher and Greg Edmonds in wanting to look for an alternative.
The Umaga plan is likely to be even more popular and, if successful, would be a public relations triumph after a season of disappointment both on and off the field.
He is seen as a coach with a good rapport with his players at Counties Manukau and is likely to relate well with a young and inexperienced Blues backline.
After playing 74 tests, the former All Blacks midfielder joined French club Toulon as a player-coach, a role he continued at Counties on his return to New Zealand in 2011.
The former Hurricane also played a season for the Chiefs on his return and has had a close relationship with the Hamilton-based franchise.
There was a feeling he could have pursued a coaching role there under Dave Rennie, an avenue which has probably been closed by the recent appointment of Tasman coach Kieran Keane.
Three years ago he missed out on the head coaching job at Munster. He then committed himself to learning his craft at Counties Manukau, telling the Herald of his respect for the jump up to Super Rugby level: "I'm not sure I'm ready for that level. I'm still making mistakes here and I'm just fortunate these guys have helped me through making my mistakes and have got the results, so I don't want to be making those at the next level.
"I want to go up there totally confident in the ideas I have. I want to make sure that they're sound and have the backing of being tried and tested," he said.
Umaga appears ready to go to the next level now, and with a clear pathway to the head coach's role in sight at the Blues, it could be a tough one for him to turn down.