The 3 high is to keep Sark from being able to easily take the top off. Force the offense to sustain consistently, drive after drive.
DCs know Sark wants to run the ball then pop the top. So, as a DC, you put 3 over top with a Nickel / SS that can play like a LB and disrupt intermediate routes or support the run. Basically run a 43 that plays like a 425, which can look like Cover 1, Cover 2, or Cover 3 if the defense can communicate once the offense shifts, etc. If the DTs and LBs are stout, the defense doesn't get completely blown up by the run game.
Patricia runs exactly this. It sounds complicated, but it's high school level defense and tOSU has elite back 7 level players that can play it easily.
I'm petty sure it's the same thing Gary Patterson ran. It's the same thing my high school ran 40 years ago. It's really simple at the base, and becomes multiple - easily - without confusing the defense.
Personally, I don't think Sark is patient enough letting the run game wear teams down. He has a good run game plan, which is why backs keep going to the league. Wear that front 7 out, so the game can get out of hand late. Make that middle Safety come up. Repeatedly.