Senior loose forward Kaino and prop Faumuina, who will be playing his final season in New Zealand before joining Toulouse in France, will be important cogs in Hansen's machine this year and they will require careful managing as Umaga seeks to start the season in the positive manner in which his team finished the last.
Anything less than four competition points against the Rebels, traditionally one of Super Rugby's weaker teams, would be deeply disappointing, yet while Umaga will be tempted to keep his big guns fresh for the New Zealand derby match against the Chiefs in Hamilton in round two, the Blues' problematic travelling record over the past few years means little can be taken for granted.
"It really depends," Umaga answered today regarding the availability of Kaino and his All Black teammates. "This is their first week with us and they've only just started a little bit of isolated contact. It's really how they take to that. I think it's a bit of a shock to the system when they start tackling each other. And especially the group he [Kaino] is in, they're not small guys."
Parsons' return is even more uncertain given his concussion suffered in September which caused headaches and fatigue.
"He's better," said Umaga, who was reluctant to put a time frame on Parsons' return. "He's out on the training field which is an improvement, it's a step closer to where he needs to get to.
"If we start trying to put demands and dates on things that puts pressure on him. I don't think that's healthy for him. It will happen when it happens."
Williams continues to make progress on his Achilles problem and is slated for a March or April return, while as far as All Blacks lock Tuipulotu is concerned, Umaga said he can only offer him support.
The absence of most of Umaga's senior players means former Crusaders lock Jimmy Tupou will captain the Blues for Saturday's pre-season match against the defending champion Hurricanes at the Blues' Alexandra Park training base.
That fixture has taken precedence of the inaugural Global 10s tournament in Brisbane the following weekend, with forwards coach Steve Jackson, who will oversee the 10s team, saying his squad would have only one training run before the tournament.
"Those guys that aren't really familiar with the 10s will get a taste for it next Wednesday, we'll have one hit-out before we leave," Jackson said.