Wasps/Blues legal battle

Hi all,
Having read the following;
http://news.bbc.co.uk/sport1/hi/rugby_union/13980334.stm
Regarding Dai Young leaving Blues to Direct Wasps.
I am interested to hear opinions on this, as far as I can tell Dai Young has a contract at the Blues. It still has time to run which would suggest to me that Wasps might have to buy him out of it, however, Dai Young resigned at the Blues, thus ending his contract and has now taken the position at Wasps.

Is this a sneaky loop hole the Blues failed to notice in Dai's contract or is this standard practice? If it is standard then why do players have to be bought out of contracts? Why don't they resign and then join a new club? If it's different for players then why isn't it the same for coaches or any other professional?