Hi Friends,
By using the highest score in a sub-caption, a judge is not trying to say that the performance was perfect. The most important task when judging is to rank the groups and rate with the appropriate spreads to ensure that the differences between two groups are reflected in the scoring. The DCA system (along with most valid (WGI, DCI) scoring systems) uses point spread guidelines to classify the score differences that should be used to differntiate between two performances.
In the case of the Buccaneers (or any other drum corps) at finals, the judges that used 100 in a sub-caption were stating that the Bucs were the best performance of the night, and the score was derived either because the point spreads dictated using that score or else it was the only higher score available in that sub-caption.
Either way, 100 doesn't necessarily mean perfect performance and to insist that the performance must be perfect before using that number is a disservice to the judge and the performers.