Football Games: Tendency for DOG+UNDER or Favorite + OVER

I will give an example of today's college football game App St vs ULL

The line tonight was @ULL -2.5 vs App St Total 69.5 or 70

O told my betting partner the game with either be DOG + UNDER or Favorite + OVER

Using my math model I had App St should have been the favorite in this game App St -3 with a total of 67 max

Out of correlation I was very sure on the UNDER but I had to wait for an APP ST +3 to get the best number. Well I found one and took it. This is a very correlated parlay

Well I was not surprised to see this correlated pair. I never did an academic study on the percentage the 2 ways this combo lands on mostly. Anyone know?

Also ... I won my bet both side and total for Today's game.