>In the absence of more detail such as the dynamics of the shapes

Baseball's have a standard diameter and shape.

It's theoretically possible that the heavier baseball has a "furry" surface or something like that, but it's such an unlikely case I didn't consider it when reading the paper.

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>it's a pretty big fail that it can't answer this properly.

I emailed the authors and they said "there could be some pre conditions we have not presented in the screenshot" and that they would address it when they released a dataset.

Sounds like it's all sorted out now. No harm done.