Just a shot in the dark here.
Could the class system set up a situation where teams seek out a more class heavy (but not exclusive) schedule to wrestle. With a more limited selection of teams to choose from to better wrestlers encounter more of top competition prior to the state finals ending several undefeated seasons early.
While in Indiana the team do not have a such a schedule and so do not always encounter as many top wrestlers prior to the semi-state portion of the tournament.
The other issue that may be a factor is that many (not all) of Indiana's undefeated wrestlers are at a much higher level than most of their competition. Thus, they are not put in a situation other than the final rounds of state to really be challenged in most years. Obviously, we have noticed this talent gap emerge over the last several years and it will take more time and work to close that gap. Ohio has been developing their talent for a much longer period than we have in Indiana. While I'm sure a talent gap exists Ohio has a much larger group of elite wrestlers allowing for a chance at more tough match-ups prior to states.
Agree the travel restrictions keep some of Indiana's wrestlers sheltered while some of the time Ohio guys end up facing more of the time wrestlers in the nation and as a result up their chances of losing a match before state. Being Ohio is also close to Pennsylvania, so some of the boarder wars battles with them could cause a person to lose their undefeated season.
I'm not sure one issue can be the main cause, but rather a combination of a little of all three reason may end up playing into why this occurs.