It means people are betting on Miami, so they are lowering the line to try and convince people to bet on Ohio State (casinos try to get equal betting on both sides)
It can also be done to head fake people playing late steam.
The handle is massively imbalanced for this game (more money on OSU) so they try to get more on Miami by making people think something is going on and the line is dropping.
It’s only gone down from 9.5 to 7.5 so not through a key number so far. That’s also important (it’s a big deal if it moves through 7 or 10)
Just one angle to consider. No one ever knows exactly why lines move.
