Better than usual for what? Does he usually do badly in the UEFA Cup? Or do you mean for octopodes in general, since most of them have no interest in football?
It would be quite simple to do a series of experiments to test Paul's abilities, but if he's limited to the World Cup, it might be tricky. How long do octopodes live?
All you have to do is run a series of tests in which the teams are represented by their names printed in black instead of the flags, to see if the colours involved have any influence. Some controls in which there is nothing representing the teams on the containers. And also make sure that the identifications when they are present are not always on the same container.
Then you do a bunch of tests for each game, to see if he always picks the same team, regardless of how it's represented, which container it's in, and what time of day it is, etc etc...
Then, once we've determined if he's successful in controlled trials, we can try and work out if he's actually psychic, or if he's actually just an enthusiastic follower of the beautiful game.