Krul knows he isn't in Rafa's plans but he wants to stay (and not play for a year) all to ensure he gets the final year of salary from his NUFC contract?
He must think himself that he's well past his best (and won't get another salary paying anywhere near what he currently gets) if he's willing to take a year off. He's only 29 years old so maybe he thinks a year off won't harm his chances of getting a new club in a year when he can leave for free?
Aye, that one year will be worth something like £2.5m to him so if he thinks he's not likely to get a decent deal wherever he ends up if he leaves now then it makes financial sense for him to hang on and take the payday. Plus, if he waits it out for a year not only does he get his inflated NUFC salary but he'll also be a free agent and so can command a much higher salary from his next club.