The wording in the title is a little odd. Basically in an MLB game, both teams have a starter. Unless it is their MLB debut, they have an ERA in the big leagues. If we looked at all the games in the MLB, what % of the games have been won by the team that had the lower starting pitcher ERA.
I would imagine that it would have to be at least over 50% of the time, but I don't know for sure.
Discus.