Today’s idiom is based on sports. It is to “be a whole new ball game”. We use it when we want to talk about when we have a bad situation and then change it in some way. Then, this change results in an improved situation. For example:
I used to hate going to work, but my old boss left the company a few weeks ago. After that, it was a whole new ball game.
My husband and I had a lot of problems in our marriage, so we went to a marriage counselor. Since then, it’s been a whole new ball game. We are much happier with each other now.
My class has the lowest grades in the whole school, but it’s because we had a terrible teacher. Now, we have a really good teacher, and it’s a whole new ball game.
Jeff wasn’t a very good athlete, but he’s been exercising a lot lately so it’s a whole new ball game.
If the situation has just changed and the improvement hasn’t yet happened, but we think it will happen in the future, we say “It’s a whole new ball game.” with the present tense. If the improvement has already happened, we say, “It was a whole new ball game.” with the past tense.
I think this idiom is based on the idea in sports, especially baseball, when a team is losing a game. Then, they change the players and suddenly they start to win. I hope this is clear to everyone.