they are called upsets because those games aren't 50/50, if it was equal pegging once a game starts the term upset would never be used.
Mate. Stop trying to learn math off the bookies. It doesn't matter what the BETTING odds are. In the real world, it's just simple probablity.
Two teams contesting one game. Therefore, either team can have one of two outcomes, they'll either win or lose. A one in two chance of winning or losing. (of course a draw is a possible result, so maybe I should say 1 in 3, but it happens so rarely I'm not even going to include that for simplicity of argument).






Betting logic is completely different.

