The only person who can enlighten us on this is a bona fide structural engineer, otherwise it is purely guess work. Me being Mechanical, structural is just guess work with some knowledge of the structure of steel wire ropes.
Give over, they are for sitting on. In normal circumstances only the ground staff will be seeing them. So why worry, on match days there will be bums on them seats. HOPEFULLY.
The cranes you mention cost a fortune to hire, so they are not going to have them sat there doing nothing. They will hire a mobile crane when they want to do a lift.