Thanks for raising this one to us. It's a bit of a strange one of course, a small part of me thinks however that if the club had agreed a contract to pay him £17.5k per week they would be obligated to follow through on that. Indicators like the % just help to give it a bit more of an at a glance context, but thinking about it from a real world perspective I can't imagine the contract write-up would be "We will pay the player 80% of their wage".
One for QA to look at a bit further, just some additional thoughts I had really on were something like this to have happened in a real world scenario.