The result was a stunning, six-tries-to-two victory, and just as impressive was the way the Blues kept the visitors scoreless in the second half. With some heavy-duty reinforcements such as Augustine Pulu and Sonny Bill Williams to come over the off-season, things are looking very promising indeed for a franchise which has underperformed for too long.
In some respects the Blues' efforts and execution came as no surprise, for they have been building towards this; they were outstanding against the Hurricanes in Wellington last weekend and the Crusaders here at Eden Park in their final game before the June break, but in those two defeats they ran out of puff and composure.
This time they grabbed the Brumbies in a headlock from the opening minutes when Jerome Kaino scored the first of his two tries, and never let go.
Even when Kaino was sinbinned in the first half for collapsing a Brumbies maul, the Blues weren't deterred. They simply kept doing what they were doing and scored two more converted tries through Sam Prattley and Matt Duffie.
That's where it became a little surreal - to see a side featuring a Wallabies midfield of Matt Toomua and Tevita Kuridrani so comprehensively outflanked and out-witted by a team playing with 14 men. "That's a good indication of where we have come to," Umaga said.
On the one hand it once again showed the paucity of the Australian conference - the only weapon the Brumbies had in their arsenal was the driving maul, from which they earned their penalty try and Matt Toomua's score - but on the other it showed the improvements the Blues have made under Umaga.
Kaino, unburdened by the captaincy, backed up his brace of tries in Wellington with another here in a storming performance either side of his yellow card, and it is now safe to say that fellow loose forward Steven Luatua is back to his best.
There was quality again from second-five Piers Francis, who left the field briefly in the first half after a clash of heads, and was superb with his linking play and goalkicking - slotting five from five.
Fullback Melani Nanai has been inspired for the past fortnight and right wing Duffie, who, like Kaino, also scored two tries, is finally finding his feet after his move from league.
The Brumbies, who saw Wallabies flanker Scott Fardy wheeled off in the second half, face the troubled Force next weekend in their final round-robin match. They are still in with a good chance of making the finals, but on this evidence will be fairly easy to work out.
The Waratahs, in the playoffs hunt and likely beneficiaries of this Blues victory, will have to tread carefully here next week; with nothing to lose the Blues are a dangerous foe.
Blues 40 (Jerome Kaino 2, Matt Duffie 2, James Parsons, Sam Prattley tries; Piers Francis 5 cons)
Brumbies 15 (Penalty try, Matt Toomua tries; Christian Leali'ifano con, pen)
Halftime: 28-15
