Complacency?? I am not so sure, how do you prepare for a debate when you opponent never sticks to one idea? Until Kerry was there on the debate floor, Bush did not know what position he would take. To me that would be impossible to prepare for. So between first debate nerves and too many positions to prepare for.....
Bush was well prepared for the second debate however. Same opponent, same old flip-flip Kerry, but he had possible answers at the ready and did a fine job.