If it affects the last-game rating the found data will be unreliable (unless PR-guy is not related to team performance, meaning the average PR-guy level should be equal...but we'd need a very big N for that
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.).
If the PR-guy has effect on total number of balls you get, it wouldn't affect it. I agree that someone wanting to do a real research on this should control for it, but I just want to have a quick look to see if there's an easy line to be found. If it leads to nothing....oh well, not much time lost.
Crunchy! If you eat fast enough