Rowing New Zealand has always prided itself on a straightforward philosophy: do the best times in training and trials and you get picked. There's no favouritism, or room for snitches here.
The stopwatches tell the story and those who have not put in over the months of training through summer until the national championships, then trials, get found out. Simple.
Last year Sullivan was initially left out, having taken his break after London to pursue other interests, notably the Coast to Coast.
A door opened to fill in as single sculling stand-in for Mahe Drysdale but it didn't work out, so Sullivan stepped away to prepare for a big tilt to get back in the squad this year. He was, according to those at Thursday's announcement, desperately disappointed.
One school of thought is that the depth of sculling talent has increased significantly, therefore Sullivan's job this year was even harder.
His early success at under 23 level through 2007-09 may at least partly have come through sheer natural talent; now the waters are choppier. Another suggestion is his technique needs adjustment and he's found making changes difficult.
His partnership with the recently retired Cohen worked a treat. They won two world titles and in 2012 had a strategy which called for a scorching finish and it worked, most spectacularly in the Olympic final.
It was the most stunning of the three gold medals New Zealand won at that regatta, with no disrespect to the peerless Drysdale or remarkably dominant coxless pair Eric Murray and Hamish Bond.
Another whisper is that RNZ staff have put plenty of time in with Sullivan to try to unlock any issues. No joy there.
He is due to meet RNZ chief executive Simon Peterson and high performance boss Alan Cotter next week.
No one wants to see Sullivan, at 26, walk away from the sport. RNZ may be in strong shape now; that doesn't mean they can easily dispense with a reigning Olympic champion.
However, a clue to Sullivan's possible thinking emerged in an exchange of tweets with Drysdale.
Sullivan on Thursday night wrote: "What do you do when the thing you loved doing is taken away from you in a day?"
Drysdale responded with a "chin up" message - "... if u want it bad enough u can get back to the top".
To which Sullivan responded yesterday: "Thanks big man but think I'll be looking at new mountains".
