The turning point would have been a realisation that it was adding nothing to her preparations for the notoriously hot Australian Open in Melbourne.
Venus told her what fun it would be. Blow that.
Wind is an issue at bigger venues than Stanley St, including the US Open where it swirls inconsistently and can be worse than what is occurring outside the confines. It comes down to attitude, and Serena Williams' fell short on this occasion.
Wind and hot air. Williams' earlier-than-expected exit in Auckland has left some fans "spewing", as the partner of one ticket holder put it to me. But that's sport. If you want absolute guarantees, forget the tennis and keep mowing the lawn.
And Williams has put Auckland on the map in an inadvertent way, with media outlets around the world reporting her shock loss.
"I struggle to think she'll come back in the future. That might just be it - a one-off appearance in Auckland for Serena Williams," said Radio Sport's Matt Brown, who lives and breathes a game he has covered around the world.
Previously Williams has played the Hopman Cup ahead of the Australian Open, the first grand slam of the year. The Hopman is a team event in Perth which she has won twice.
Drop a match and you can still play the next day, which makes for a more certain Aussie Open preparation.
In some ways, Williams took a risk coming here, a risk she didn't need to take. We should thank her for that.
We put common values on uncommon people. Stars of Williams' standing live in a world, a bubble, impossible to imagine. They can't always find top speed - as in Tiger Woods did not win when he played the New Zealand Open during the peak of his powers.
That still doesn't adequately explain 88 unforced errors from Williams against Brengle. We deserved better than that, much better. That she came here in the first place though is still a wonderful coup.
Thanks for the unexpected memories Serena. Hopefully a little bit of wind won't stop you coming back. But the chances that a player of her standing would return anyway were probably fairly slim.