Ben Ainslie's unfamiliarity with new role was evident even during pre-race drills.
If confirmation is needed of the disarray in which Oracle Team USA find themselves, look no further than the John Kostecki-Ben Ainslie debacle.
Kostecki is the 49-year-old tactician who was one of the heroes in Oracle's big boat challenge against Alinghi to lift the Cup in 2010. The 10-times world champion and Olympic medallist cut his sailing teeth on San Francisco Bay but got the blame for a race-turning attempted foil-tack in Race 5 on Wednesday.
Kostecki was dropped from the race crew and replaced as tactician by Briton Ainslie, regarded by many (including Oracle skipper Jimmy Spithill) as the best sailor in the world.
Many yachting observers believe this was a Larry Ellison decision. Spithill denied that, saying it was his alone. However, the events of yesterday proved not only that it was an ineffective ploy but that it was unlikely to have been solely the province of single-minded sailors such as Spithill or Russell Coutts, Oracle's CEO.
Both seem too practically minded to assume that just changing a tactician would benefit a boat that is lacking in speed, compared with the opposition's.
In addition, Ainslie has been employed as skipper of Oracle's other boat, the reserve boat. He has done nothing other than steer up until now.
The tactician's role is different. Not only does he call the moves, he must also help with the head-down hard work, slugging it out on the taxing handles of the grinders which operate the hydraulics to power the boat. Ainslie's unfamiliarity with this role was seen before the start when Oracle was going through some pre-race drills. Ainslie started to head off for the other side of the boat, sprinting over the trapeze. Then he stopped, realising he was in the wrong place - and headed back. It was ample illustration of his uncertainty in the role on these boats.
Worse was to come. At the bottom mark, with Oracle ahead by 12s in Race 6, Oracle decided to split on the upwind leg - instead of the more usual match-racing tactic of covering the boat behind; moving to head them off and stay in front.
With the advantage of separation, Team New Zealand settled in to making their boat go faster upwind and dragged Oracle into a tacking duel - doing 14 to the American boat's 15, an exhausting effort for the grinders. There were a couple of lead changes but Emirates Team NZ got their nose in front and tactician Ray Davies turned the screw, forcing them into tacking, Oracle's weak point.
The decision to split is generally the tactician's call. The onboard microphones seemed to pick up the voice of Tom Slingsby, the young Australian Olympic hero and tactician-grinder on Oracle, more often than not. Maybe he made the call for the split but, if so, why bring Ainslie on board?
If it was in fact Ainslie's call, it was an error at least the equal of Kostecki's.
"Both John Kostecki and Ben Ainslie are fantastic sailors," said Spithill.
"We are very lucky we can rotate guys like that. [The team] discussed it and thought it was a good idea.
"It was my decision. I haven't spoken to Larry Ellison since before the [Cup match] racing started. I talked to John and told him what we were thinking. He went straight over and started getting Ben up to speed on things. That's the sort of guy he is; it's all about the team with him."
Nevertheless, the swap of tactician made no difference. In Race 6, on the definitive upwind leg, the New Zealand boat trailed before gaining 56s on Oracle in winning by 47s; in Race 7, they led all the way, gaining 49s in the upwind leg before winning by 1m 6s.
The Kiwis also proved quicker in some of the downwind and reaching legs yesterday.
There is little a tactician can do about that.