Because Brad Friedel could die at any minute from old-age, Harry Redknapp requires a really great goalkeeper to take over from him and be a great second choice at the moment. And because Tim Krul is ridiculously good this season, he's a good choice!
Despite looking like what happens when you glue googly eyes on a broom, Tim Krul has been outstanding and is about 70% of the reason Newcastle currently sit in 6th place, or wherever it is that they are just now. At just 23 he also has a long career ahead of him, especially if he stays fit like Friedel, who was not only already a professional footballer at the time of Krul's birth, but had overseen victory during the American civil war and the birth of Jesus, so for Spurs it would be great business. The only sticking point for the North London side might be the transfer fee that Newcastle demand for their shot-stopper which based on previous evidence will probably be "anything that makes the chairman's eyes go £££ like in a cartoon. So.... £5?"