Installing 9.8 x9.8 on a 10x10x10x cage will I have any openings on the left and right side where the ball could bounce off the left /right poles?

Hello Josh,
Thank you for contacting TheTerakart.
There might be openings on the left and the right side, depending upon the setup and it is recommended to use padding on the poles to avoid bouncing back.
Should you have any questions or concerns please feel welcome to reach out.
Regrads,
Anna(TheTerakart)