If they had been more clinical for longer - instead of just 50 minutes - they would have been home and hosed with time to spare.
But no. The lineout was a shambles on that bad patch. Total botched job. There was no confidence, no timing and no clean possession.
It's been a problem all year for the Chiefs but last night was the one night when they really needed it to go well for them.
Their defence was the other big part they had to get right. Their two titles were built on their linespeed and accuracy - both of which have been sporadic this season. Their tackling was something they were desperate to nail down tight and yet by half-time they had missed 28.
It was crippling for them - especially when about half of them were on one man. Henry Speight was tearing them apart from the right wing.
The legions of dummy runners the Brumbies put in front of the ball caused some confusion, but it was basic one-on-one tackling that was the problem for the Chiefs.
They fell off too many, just as the forwards lacked a little urgency and awareness with their pick and go work.
There was no gripe with the validity of the tactic, it was the execution: too often the ball carrier was isolated. Too often the next wave of support was too slow getting there.
Knock out football is not the place where teams can even be half a metre off the pace and the Chiefs paid big time for their lethargy.
They were also, possibly, a little unfortunate that Tim Nanai-Williams was yellow-carded after three minutes for not rolling away.
The Brumbies scored two tries while he was off and slipped into a damaging flow and rhythm. They were playing the game at one pace - the Chiefs another.
A Chiefs victory looked almost impossible. The Chiefs even clawing their way back into the game and finding any kind of respectability looked almost impossible.
They were shell-shocked. They were barely hanging on and they didn't seem to ever have the ball. All that tackling, all that scrambling...it looked as if a few of the Chiefs players were already thinking about where that would leave them physically later in the game.
Bundee Aki's short blast over the line restored their faith and they were able to head to the break in touch. A rark up from the coaches and out they came a different team. A team that didn't die wondering.
But they did die. They gave away too much, too early and the team that are the masters at winning these super tight games - no longer are.
Brumbies 32 (N. White, R. Coleman, J. Mogg, J. Butler tries; C. Leali'ifano 3 cons, 2 pens)
Chiefs 30 (B. Aki, T. Kawera-Barlow, T. Nanai-Williams, G. Anscombe tries; A. Cruden 2 pens, 2 cons)