Damo, not going to get too involved in this (not least because the supporting cast is a tad unfair), but...
Or anything where there is regulation to be in compliance with. All accounting is done within legal and regulatory frameworks, and they vary depending on the industry. Sports may have different rules to apply, but they are not unique in having a framework to operate in.
I sort of get where you are coming from with this, but the lawyers etc are only going to get involved using the figure accountants have generated for them. And again this is not unique to sports law, in any walk of business life its the lawyers who get involved when there is quibbling to be done.
I run computer systems. I still understand that it doesn't matter what sphere you are in, accounting is still applying the rules of that industry to arrive at a fiscal position. And in this case the rule is that you are allowed to count player trading gain when calculating revenues. Exchanging a cash asset for a fixed asset isn't revenue altering one way or the other. Depreciating those assets is a different scenario of course.