"The deal with the players was, 'Look we're all in this together and we need to keep the game clean. If you are approached to fix, it's not going to be us playing a game. It'll be someone trying to do a fix for real, a media scam, or a bit of both. Either way you will face serious consequences. Make no mistake, we are not going to try to set you up or play games as a unit. That's part of the deal.'"

That is Lord Paul Condon, the founder and former chairman of the Anti-Corruption and Security Unit (ACSU), speaking to Ed Hawkins for the latter's 2012 book on cricket corruption, Bookie Gambler Fixer Spy. Condon was responding to a specific query, one he had answered more times than he cared to, about why the ACSU could not be proactive and instigate sting operations of the kind the News of the World (NOTW) had in nabbing Salman Butt, Mohammad Amir and Mohammad Asif.

This is now a well-aired clause in any dissection of the ACSU's performance, though it is no less reasonable for it. As Condon explained, the ACSU is not a newspaper or a police force; if the ACSU entrapped players the resulting case would likely not make it to court because of the many ethical and legal issues it would create in doing so in the first place.

But one finds in that response something of greater interest, which is the way in which the idea of trust underpins it. We're all in this together. We will not screw you over. We have a deal. Trust us.

We do not know the extent of how much players do or don't trust the ACSU, but it is reasonable to assume that Brendon McCullum, who made his views clear at the MCC's Spirit of Cricket lecture, does not stand alone. Tim May, as a relevant example, was fretting about a trust deficit among players with the ACSU as long ago as 2010.

What is immediately striking about McCullum's criticism is that it is not the usual potshot, the one Condon was responding to. And it is more than the leaking of his testimony, which, although obviously worrisome, was likely the debris of a politically delicate moment in the affairs of the ACSU and cricket administration.

It is his description of the manner in which the ACSU handled his first reporting of the alleged approach made to him by Chris Cairns: "[The ACSU investigator, John] Rhodes took notes - he did not record our conversation. He said he would get what I said down on paper and that it would probably end up at the bottom of the file with nothing eventuating. Looking back on this, I am very surprised by what I perceive to be a very casual approach to gathering evidence. I was reporting two approaches by a former international star of the game. I was not asked to elaborate on anything I said and I signed a statement that was essentially nothing more than a skeleton outline."

Later, the ACSU would record another statement, which, McCullum reasoned not outrageously, confirmed the first statement was inadequate. And just how casual that first interaction really was became apparent during Cairns' perjury trial late last year in London. There it emerged that Rhodes had lost his diary that chronicled the period around McCullum's report.

"The ICC will argue that for every leak dozens, maybe hundreds of other testimonies and investigations remain secret, and they are probably right. But, like wicketkeepers, it is the misses that shape perceptions"

This is what is most alarming, that what should presumably be the easier bit - recording a detailed and thorough statement of an approach - was bungled so. What hopes, then, of the actual investigation, had one followed? McCullum first approached the ACSU in February 2011, not six months gone from the NOTW sting. In this casualness during a period when the natural reaction should have been to be extra vigilant - to the point, even, of being a little paranoid - is where the trust disappeared.

Perhaps this attitude should be no surprise, given the defence provided by Rhodes' boss at the time, Ravi Sawani. Action was not taken on the allegation, Sawani now says misleadingly, because Cairns was "not under ICC jurisdiction", that he was with the ICL at the time the alleged approaches were made. How does this even make sense? The alleged approach was not for McCullum to fix games in the ICL - McCullum was playing sanctioned cricket. Is there a clause we missed in the ACSU code that requires its investigators to demarcate between unsanctioned and sanctioned sources?

If there is a saving grace, it is that McCullum spoke of his experiences of five years ago. Since then, the ACSU has been the subject of two wide-ranging reviews, the first by Bertrand de Speville in late 2011 and more recently by John Abbott. All recommendations from the latter were adopted in 2015; some, not all, of de Speville's recommendations were as well.

According to the ICC, in combination they have led to a significant change in how the ACSU operates now, that its "processes, procedures and resources… have been further bolstered and strengthened". When the ACSU investigated the case of Hong Kong's Irfan Ahmed recently, for instance, they made sure that an ICC lawyer was present during questioning by ACSU officials, just as McCullum wished one had been when he first met Rhodes. Had he been properly advised and briefed then of the implications of what he was saying, he may not have had to face his statements being questioned for inconsistencies as they were by Cairns' lawyer.

The ICC has also signed an agreement with Sportradar, a UK firm renowned for tracking betting patterns in sport, and is enhancing its cooperation with law-enforcement agencies in various countries. It has expanded the ACSU's workforce, adding analysts of betting patterns to make a core team of 15, though possibly it is still not enough: there are still only five regional security managers to cover the entire cricket world, one of whom, improbably, is tasked to cover England and the West Indies together (de Speville recommended five more).

They also claim to have put in "strong measures" to ensure that leaks such as that of McCullum's ACSU statement do not occur again, measures which primarily include narrowing the number of people who have access to such information. Those leaks, though, they are what erode trust most visibly, and it is an issue de Speville had also highlighted in his review: "… information that comes into the unit is not as secure as it should be."

The ICC will argue that for every leak dozens, maybe hundreds of other approaches, testimonies and investigations remain secret, and they are probably right. But, like wicketkeepers, it is the misses that shape perceptions and calibrate the trust implicit in Condon's words.