There are...

they 'let him score' because they knew their asses were kicked and they couldn't stop him anyway.... not because the coach told them to.  LOL

I don't think it really matters much. When Ohio State kicked off after their last touchdown, their best chance to win the game was to stop Michigan, get the ball back and score a touchdown and a two-point conversion to hopefully force overtime.

They were completely unable to stop Michigan's running game on the last drive, though. After the fantastic Haskins run gave Michigan a first and goal at the 5, Ohio State had no good choices.

From a game theory perspective, letting Haskins score might have been their best chance to win the game at that point. The most realistic best case scenario if Ohio State plays tough defense down is Michigan runs off a minute or two on the clock and kicks a field goal to go up 38-27. They'd still need to score twice, but with a minute or two less time to do it.

If Ohio State had managed to contest that last touchdown, Michigan likely would have run a minute or two off the clock and scored a touchdown anyway. Which is the worst scenario for Ohio State, and Day might have thought it likely. 

Regardless of whether or not it was a conscious decision, the Ohio State defense was unable to stop Michigan at that point.  

I don't remember the timeout situation, but the theory is, if they're 2 yards from scoring, your biggest enemy isn't the score, but the clock. Say you stop them twice (Michigan would have been fine with this) but the clock still runs or you have to use up valuable timeouts. They're likely to score anyhow, so would you rather they score with 2 minutes left or with 30 seconds left? You have better odds of scoring twice with more time on the clock.

2:18 left before we snapped the ball at the 4 yard line 1st and goal. With the way we were running the ball, we’re likely to score a TD on downs 1-3. If we don’t get in on 1st or 2nd down, they’ve now burned 2 time outs and we’ve still scored on 3rd down so they wasted their timeouts for nothing. Don’t get in on 3rd down? Clock is likely down to 1:20 before the ball is snapped on 4th down and we kick a field goal to go up 11. Having 1:20 & zero timeouts to score twice is much harder than having 2:17 & two timeouts. 

not unlike pulling the goalie in hockey or fouling a good free throw shooter in basketball....  desperate attempts to give yourself a chance.  low rate of success, they rarely work in your favor, but whether you lose by 1, 2 or 7.... you still lose, so there's little down side.

from your mouth to God's ears