It's a belief based on a series of recent occasions such as sending players into the Sunderland away sections, SKP, Nyron, etc, the International Fans Day, etc. Incidentally I like and appreciate these initiatives on principle but it does mean tickets are taken from regular Sunderland travellers. The Everton and Liverpool games were sold out meaning hundreds were unable to buy tickets.
There's naturally more pressure on the club now, being in the PL, to provide tickets to corporate clients, etc. The ever changing regulations and lack of communication between supporters and the ticket office is a regular issue on forums, etc. At the Newcastle away game, for example, I was in the lift and talked to a group of people who'd come over from Strasbourg. On the way home I sat with Talbi's parents. One of the Sunderland first team players gave a couple of tickets to joiners who'd done some work for him, that's documented.
I'm well aware that various people are entitled to tickets, player's families or whoever, but I do suspect the way 60 tickets suddenly became available was a little too convenient ...
... they've had plenty of time to contact those who unjustly had tickets taken from them, it hasn't happened.