There are two sides to the resting players issue. For most players it is hard to come in off the bench and get into the flow of the game immediately, or to adjust to the energy of the crowd. I still think you are way overblowing the issue. When you are young, many players play a LOT more than 40 min many days. Sure, it isn't always the same intensity, but most (not JoshO) can play a much more than 40 minutes. I think there are occasions in games when there aren't breaks for FTs or timeouts, where players get winded, but these guys generally get better when they have played big minutes, not worse.