I am not sure pressing the most physically gifted WR in the country is a great idea. Day is not a moron, he will have plenty of man beaters in his play book. We saw crossing routes in that film.
Cover 2 man is not a great run coverage. You are asking for front to stop the run game with honest numbers. I assume OSU will try to establish the run game. That said If Texas can stop the run with honest numbers, OSU will struggle to score.
You are assuming an offense with a QB starting his 1st game is capable of executing 10 play drives to score. I am not convinced that is the case. That is generally something PK bets on. Is it a bad game plan to force OSU to execute, bet that Texas will get them behind the chains over a course of a long drive, and lean on your pass rushers to end it?
Relying on press man will require 1st round NFL CB talent and that is not even a lock, because OSU has 1st round NFL WR talent. I could see PK mixing in more coverages. We will see Cover 3. He can also mix in some Cover 3 Cloud (roll up a CB to the flats on one side). Throw in some man and Cover 2/4 and some blitz packages. I think the worse thing to do vs a new QB is let him get comfortable with the coverage. That is why I brought up Ewers vs Bama. Sayin is a talented QB, if he knows where to go with the ball, he will have success. Mix up the looks make him hold the ball an extra second or 2 and hopefully that allows Colin to impact the game.