RG mentioned on the Codemasters forums that the game would most likely be hard to edit (i.e. not having a very open file system) because that's what most Codemaster's games are like. His words (well, not exactly) not mine.
Cricket 2005 is very likely to be editable in terms of graphics, player stats and tournaments because Rugby 2005 was. I only said "likely to be" before all you lot tell me "how the hell could I know" and all that bollocks.
The Cricket 2005 graphics will most likely be in the same format as thr Rugby 2005 and FIFA files. I know a bit about most of the editors for this type of graphics format.
I'm going to guess that the cricket_pc.gob file will still be called exactly that, but will be a ".big" file in format - this is the same as Rugby 2005 and FIFA and there are plenty of extractors available for this file type.
If I'm wrong, we've got a whole lot of work up ahead...