My guess is its a couple sub levels bonus in stamina and/or enthusiasm depending on the level of the PR guy. So if you keep both of those maxed out constantly it may be no help at all or it could be the difference in getting the win at the end of a close game when the players are exhausted and you need that loose ball. I use an Advanced PR guy with CI to keep butts in the seats and I have 2 home losses in the last 2 seasons going 22-12 overall.