There’s a old essay on the subject by James Michener (Bicentennial) who, if I recall, concluded that the major contributory factor in home advantage was the vulnerability of the officials to psychological pressure. I don’t know if Runiman’s seen it.
On reading his stuff in the LRB I had formed the impression that Runciman was probably in his sixties. I couldn’t tell you why, but I was startled to look him up just now and find he was younger than I am. I imagine this sort of thing is going to keep happening.