Perhaps the unsung hero of Oracle Team USA's resurgence in the America's Cup is the cherub-faced 26-year-old Australian, Tom Slingsby.
He is working the wingsail on Oracle's boat and is becoming the glue in the way he, Spithill and tactician Sir Ben Ainslie are a firm combination.
There is, in that, a not-so-enjoyable echo from Valencia 2007 beginning to reverberate around the 2013 America's Cup campaign. That was when Alinghi successfully defended the cup against Team New Zealand's challenge by 5-2.
The Swiss syndicate had a slightly faster boat but it also had a polished crew with Kiwi skipper Brad Butterworth perhaps winning the prize for the most influential sailor of the regatta and the best spotter of wind shifts.
Butterworth was 20 per cent of the famous (or infamous) Kiwi tight five who jumped ship after Team NZ's successful 2000 campaign to join Alinghi - along with Simon Daubney, Warwick Fleury, Murray Jones and Dean Phipps.
As in any sport, good combinations often result in good understanding and decisions, giving a team an edge. That combination was a big part of Alinghi's success in 2007 and, after yesterday's races in which boat positioning and wind spotting played a large part, there was a slightly uncomfortable sense of deja vu. Daubney and Jones are in Oracle Team USA now, though neither is in the sailing crew defending the Cup against Emirates Team NZ.
But the echo that doesn't sound so good is that, as Alinghi did, the "tight three" combination in Oracle's boat appears to be genuinely gelling, helping their charge from an apparently hopeless position to one of gathering strength.
Certainly, to the naked eye, Oracle's boat appears to be quicker - particularly on the reach and on the downwind runs, though some of that might be due to the natural advantage gained by being the lead boat and the "dead" air that trails it.
But the improvement in boat handling has coincided with the appearance of Ainslie as tactician and the co-ordination with Spithill and Slingsby, like Ainslie an Olympic gold medallist in London last year (in the Laser class).
Slingsby, acting as wing trimmer, was given extraordinary praise by Oracle chief executive Sir Russell Coutts, pre-regatta. Talking about Artemis' Nathan Outteridge and Slingsby, Coutts said: "I think these two are the future of sailing. They are both so incredibly mature, especially in dealing with a big team like this.
"I look back at myself and there's no way I could have handled what Tom Slingsby is doing at 26. You put him in a room with designers and sailors and people listen. They have been brought up in a new era and it shows."
After Ainslie replaced local San Francisco sailor John Kostecki on the boat, the trio immediately began talking about improved communication. At first, it sounded like a slightly desperate exercise in self-belief but, after a near-flawless exhibition of sailing yesterday, the combination between the Olympic gold medallists and the America's Cup winner (Spithill) seems to be paying off.
They have now won four races in a row, though that must be leavened with the fact that Team NZ were leading in the last three races to be called off because of the 34th America's Cup plethora of rules.
Oracle have won, in fact, six out of the last eight sailed. The effect of combination was touched on by Butterworth after Alinghi's victory in 2007: "It is excellent to sail together ... it makes our friendship better and our skills better and we want to do it again. It's important [to stay together] because that has been our career and our strength.
"Why would we break that up? We are now a team that is well established and we [the tight five] have got a lot of ownership of this team."
None of this should be interpreted as suggesting that Team NZ don't have that same sort of combination and understanding. They do. Most of this team have been together for 10 years and it has shown all regatta.
Barker, Ray Davies and Glenn Ashby are the brains trust on board Team NZ's boat and Adam Beashel is also a renowned wind spotter (if he is ever able to pop his head up from his grinding).
It's just that, at the moment, they are not quite gelling. Yesterday, in an admittedly difficult day when the wind shouted and then disappeared, two poor direction decisions cost the Kiwis. Davies, who has had an otherwise excellent regatta, may have called it wrong while Slingsby, who seems to be making the wind calls, is getting it right at this juncture.
The boat is still competitive, the Team NZ sailors have set the pace this whole regatta. But this is a marathon, not a sprint, and the Kiwis seem to have a bit of a pebble in their shoe at the moment.