The GAA's projections for Proposal B at next week's Special Congress are "very, very conservative" - that's according to Conor O'Donoghue.
Delegates will vote next week on proposals to radically change the landscape of the All Ireland Senior Football Championship.
On Thursday night, GAA finance director Ger Mulryan presented figures to county treasurers which claimed that Proposal B would be the least financially beneficial of the options on the table.
His estimates suggested a championship with a backdoor system and Tailteann Cup would generate a net figure of €19.6million.
According to Mulryan's figures, Proposal A would deliver net revenue of €19.3million, with Proposal B bringing in €18.8million.
Earlier this week, O'Donoghue - who helped draft the proposals as part of the Fixtures Review Task Force - projected an increase in revenue to the tune of approximately €10million euro if Proposal B wins the day at Special Congress.
Mulryan's projections were based on average league attendances of 8,000 to 9,000, whereas O'Donoghue's figures were based off an average Super-8's attendance of 18,500.
But speaking to Friday night's Off The Ball, O'Donoghue said his methodology delivers a more realistic model for Proposal B.
"They [GAA] disagree with that process," he said, "And they've come up and said 'no no no, you can't use that, you've got to use the actual National League figures from February'... and then an average ticket price of €11 - including concessions.
"So that's the way that they've looked at it, and they're perfectly entitled to do that.
"I disagree. I disagree profoundly. I believe there's much more value in the games programme in the summer than has been described - but that's my opinion.
"These are assumptions based on the future. I've based my assumptions on the evidence, they've based their assumptions on different evidence and they're perfectly entitle to do that. There's a debate.
"The central part, which I took from it was those assumptions that have been forwarded by Croke Park are very, very conservative I would say.
"And that's fine. And yet, they still arrived at a number that meant all of the various proposals would run very similar to each other according to what they've said. And that's fine also.
"But it does answer the question that [Ulster GAA Secretary] Brian McAvoy and others asked publicly - and were right to do so, 'Show me the figures. Where are the figures?'
"Everyone has been shown two sets of figures based on assumptions into the future. Those assumptions are things that are unknowable right now.
"We based them on evidence that we think is reasonable, and I don't doubt that Croke Park also feel - or that certainly Ger [Mulryan] feels that those numbers that he's gotten from the provincial CFOs etc, and they would have sat down as I understand over the last day or two to go through figure... they're perfectly entitled to put them out there, and it's up to you or I to argue the case after that."
Earlier in the day, the GPA - who are strongly behind Proposal B - welcomed the GAA's figures, saying "There will be no meaningful financial impact should Proposal B be backed at Special Congress, with only a 4.1 per cent difference between any eventuality using the GAA's surprisingly conservative attendance figures.
"Given that this has been a concern expressed, we’re happy to see it now clarified as it should put delegates’ minds at ease on this matter."
On Friday's Off The Ball, O'Donoghue raised the example of the Munster Hurling Championship as a support for the case of Proposal B.
He outlined the increased revenues that came after its switch from a straight-knockout/backdoor system to a round-robin format.
"People said that when there was no more knockout, it was going to kill the Munster Championship," said O'Donoghue.
"I have Munster Hurling Championship figures there, and I was interested... obviously Ciaran Leddy - who is also entitled to come out with whatever figures he wants to come out with.
"So in 2016 the Munster hurling receipts were €1.9million.
"In 2019, the last pre-Covid year, they were €4.2million.
"I think that's a second, very serious, data point that we could rely on.
"So what they're telling us is, that the Senior inter-county Hurling Championship - that brought in €4.2million - the games in that alone would exceed by a million euro all of the football games, in all of the football championships - the 112 games - that's hard for me to believe.
"But listen, everyone has an opinion on that. So it's not one data point, there are a number of data points.
"But again this is the future, so we don't know what the future is going to look like. And people are entitled to put whatever figures they want into the domain, and it's up to people to debate those figures after that."