First of all Yes. MD and Bosco are dominant teams. Let's not hide from that fact, definite powerhouses.
However, it's not just and only that. DeLsalle folks have it correct and are right when they say EXECUTION is a major factor. To say Serra executed a game plan at a high level is incorrect. Blocked punts and several special teams miscues. Fumbles everywhere especially on regular snap exchanges. Blown coverages where receivers broke straight down the middle of the field for bombs. Even DeLasalle would say beat our team short, but you ain't gonna beat us deep. For Mater Dei, short, medium as well as Long was wide open all night.
Serra had Zero points. ZERO. DeLasalle scored points and were competitive, why? Their EXECUTION.
DeLasalle has played a national schedule before in the past. So does MD and Bosco. Serra I don't think plays a tough preseason schedule.
So for sure a tough title game for Serra, but one cannot say definite reason was dominance. Serra execution and preparedness was sorely lacking