Off one’s own bat = on one’s own initiative; without being asked to do by anyone else.
- Whatever she did she did off her own bat.
- No one asked him to help; he did it off his own bat.
- Rozanne didn’t wait for her parents to tell her to take out the garbage. She did it off her own bat.
Play ball = co-operate in order to achieve something ( usually used in negative context)
- Because he refused to play ball with these criminals, he was shot and seriously injured.
- If you play ball, we will be reducing your sentence from 8 years to just two.
- Just play ball and do what they say, and nobody will hurt you.
On a level playing ground/field = in a fair situation where everyone has an equal chance of succeeding.
- All applicants have to agree to the same conditions for the interview in order to ensure a level playing ground.
- They are still not providing a level playing ground in terms of opportunities for women.
- The new legislation is intended to create a level playing field for students of all backgrounds.