Team New Zealand "cracked" under pressure leading to their spectacular crash during practice racing, according to one veteran observer.
And TNZ skipper Peter Burling has admitted the capsize would have blown previous boats to pieces.
The America's Cup defenders will be licking their wounds and carefully checking their systems after capsizing during the first day of practice racing on Course E, near Maraetai.
Te Rehutai was quickly righted after it was dumped in the water during a race against Sir Ben Ainslie's vastly improved Ineos Team UK in an estimated 35 knots. But the TNZ boat was towed back to base.
The crash has breathed extra life into the America's Cup with the defenders – seen as invincible by many prior to the regatta – continuing to show some vulnerability.
UK newspaper The Times described the capsize as an "embarrassing setback" while claiming the British team – who were left red faced by the December racing – were "looking more on the pace".
Team New Zealand's own video of Monday evening's incident, which they posted on social media, heightened the drama and made it clear just how dangerous and thrilling racing in the AC75 class can be.
TNZ initially downplayed the crash a little, tweeting: "Nothing like a bit of drama on the Waitemata, the first swim for Te Rehutai."
Burling said yesterday they had got "a bit too high in the jibe and stopped pretty quick".
"It's a pretty big load on the bow when it hits, we just wanted to do some checks, but everything functionally was working pretty well on the boat – so we just towed in on the foil," he said.
"If you'd done that same kind of manoeuvre on the cat on Bermuda, you'd be in hundreds of pieces. Full credit to the design of these boats that they are still in one piece."
Wing controller Glenn Ashby admitted "the capsize wasn't ideal".
"But it's a fantastic opportunity to push ourselves and push the boat hard against an opponent.
"Ben and the British guys did a fantastic job today – they started extremely well and they were excellent opponents for us around the track.
"So hats off to those guys … pretty exciting yachting and one of those ones that at the end of the day, everyone is enjoying the practice."
TNZ were about 50 metres ahead of Ineos when the crash occurred. The boat nosedived as they leaned leeward and the opposite foil came out of the water.
Coach Ray Davies said the boat "leant over a lot more than normal and over she went".
"I don't know if we had a control problem or exactly what happened," he said.
Ainslie also won both starts against Burling, in a bad day for the America's Cup defenders.
Writing in Sail-World, Richard Gladwell said TNZ were putting the crash down to "operator error, after the crew lost control after a high speed gybe at the end of a windward leeward".
"They were under pressure from a much improved INEOS Team UK - who took the practice racing seriously and took to the home team with a match racing tactical strategy," Gladwell wrote.
"It was vintage Ainslie applying relentless pressure and four-time Olympic Gold medalist got the reigning America's Cup champions to crack.
"Had this been a Cup Match, the Brits would have come away with the points for a win. And had this been the opening day of AC36, the Brits would be cock-a-hoop - and rightfully so.
"Ben Ainslie looked like he could push the boat hard, and made the seemingly invincible Kiwi team crack under pressure.
"That is not to say Emirates Team New Zealand were not impressive - as seen in the ACWS, when the occasion warranted, they can definitely find a fifth gear/light the afterburner when the need arises."
French website Foil and Foilers also analysed what went wrong for TNZ.
"In exiting the jibe, it seems that the upwind foil was not hauled up fast enough, or the leeward foil descended too late, barely a second, giving the boat a heel which slowed down considerably," the article noted.
"The apparent wind suddenly recedes, coming more to the side of the boat. The sails are overflowing, but impossible on these boats to drop everything. The boat sets off again, but too high, the rudder comes out of the water, and there it is: the bow engages, the boat comes to a complete stop and lies down on its side."
Heading into the Cup racing?
• Be aware that traffic will be busy, and parking will be very limited.
• Give yourself plenty of time and think about catching a ferry, train or bus instead.
• Make sure your AT HOP card is in your pocket. It's the best way to ride to the Cup.
• For more ways to enjoy race day, visit at.govt.nz/americascup.