Yes it was a bad day . You cant seriously tell me that Hawthorn are a 10 goal better side than Sydney especially when honours were even and quite close in the games they both played against each other during the season. Sydney had a lot of players down on grand final day and they didn't perform. It happens to even the best sides. Mitchell might be flying at pre season training but so is about two thirds of the competition at the moment and it doesn't mean hes a walk up start in round 1You don't lose a GF by 10 goals and write it off as a bad day and stick with the same set-up for the next season. They need to try new things. They need to get better. Changes will be made. Longmire has already hinted at some changes, such as Sam Reid being used down back. Malceski leaving will also result in some changes obviously.
Mitchell has apparently been flying this pre-season and winning time trials so he will be right up there. His injuries from early in the season probably effected his overall fitness level going forward too. Don't underestimate the improvement continuity in training can bring.