I'm not a medical person but I'd say it's very hard to generalise this as there could be all kinds of factors involved. There could be all kinds of other things going on (extreme bleeding, difficulties in getting oxygen in, I imagine the possibilities are huge!). Other factors such as age and state of general health and fitness could, I'd assume, factor into how much the body could take in efforts to rescucitate.
I thought maybe his heart rate was coming and going and maybe reacting to shocks, hence the amount of shocks, in order for them to keep shocking, rather than it being completely dead - I have no idea though medically if that's a possibility.
This was a fit young man with, I assume, no recognised serious medical issues intervening as footballers are apparently checked regularly health wise. I'd have thought it had been found he had any kind of condition which meant what did happen might have I'd wouldn't have thought he'd be out on the pitch in the first place.