We should care far more about game play, than about it being realistic. If there are reasons stamina doesn't work because of game play, then let's talk about that. I think the biggest thing with stamina continues to be the use of 5 very expensive star players at the top end of the game. Making it easier to train (by arena/staff/etc) doesn't really address that situation, unless you make it easier to train but have a lower cap on it. Similar to FT, change the distribution of the effects of the skill.