World Cup surely, especially after the game last weekend was postponed.
We've got nine league games, and nine weeks, before the break (assuming the game isn't rescheduled this side of it) and the winter window opens. Bringing in anyone now who hasn't had a preseason then it's going to probably take them half that time just to get up to match fitness. With Costa our need for another striker was so urgent that even if we only have him for 4-5 of those pre-WC games it's worth it, but we'd have to be extraordinarily unlucky to end up as desperate for another CB this side of January.