Quote ="Jake the Peg"He knows how much he's earning'"
Yep.
Quote ="Jake the Peg"what is published he's earning'"
How often is what a player's earning published? Accurately?
Quote ="Jake the Peg"and how he's being paid it.'"
Yep.
Quote ="Jake the Peg"He will also know how much some of his colleagues are being paid'"
Probably.
Quote ="Jake the Peg"what comparable players are being paid elsewhere'"
Completely irrelevant and inconsistent.
Quote ="Jake the Peg"roughly what the going rate is for someone in his position with his level of experience'"
What?! Seriously?
Quote ="Jake the Peg"what he was offered elsewhere'"
Assuming he's been offered other contracts, this is entirely dependent on so many other factors as to be useless information.
Quote ="Jake the Peg"and where roughly, in the club's wage structure he will be.'"
Possibly, but knowing your place in the structure doesn't mean you have any idea what the other players are earning.
Quote ="Jake the Peg"Now you may get some really dumb players who can't piece all of that together but I'm guessing most of them would'"
You're guessing most players would be able to piece together how much they are earning, how it is being paid, roughly what some team-mates might be getting and a rough guess of their place in the wage structure and deduce from that that the club is definitely deliberately and consistently cheating the salary cap? Time to set up the rugby league detective agency I think; Holmes, Marple, et al. will be out of jobs in no time.