Now that I think about it, the ball of hard pus in her eye looks *exactly* like my first encounter with cellulitis. Basically it had gone untreated for longer (I learned very quickly when it was cellulitis, thus to go in to urgent care), and it had formed just that kind of ball of pus. The skin had sort of come off the 'hole' at that point, so it looked a lot like that. And sure enough, a pus 'turd' came out, 1cm long and 0.5 cm thick. My calf has largely returned to normal - if I'm careful checking though, I can still feel the faintest indentation from the toll that infection took, years later.
Basically (sorry I rambled!) I agree with your assessment, Shelagh - when the scab comes off, the opening should be wide enough for the 'turd' to come out easily and without a lot of hassle.