If a player is in contract negotiations, then whilst he can't sign for another club, is there anything to stop him checking?
I would imagine it goes Hull offer Manu a contract, his agents goes , hmmm I can probably get better for you (ME) elsewhere. They turn down the offer. At this point the club can
1. enforce anti-tampering
2. offer a better deal.
3. Say that's our best deal but you are more than welcome to have a look and see if you can get better
My understanding of the deadline means he cannot sign for another club, so Hull will always get the last say, in that they can offer a contract at the last minute to snatch him back, as he will not have been able to sign anything till after the deadline. But maybe a check on the rules is needed.