Are you talking about stamina or game shape? If you're talking about game shape, the answer is simple - inside the game's code, there are hidden sublevels of game shape and all of the other skills (including stamina), meaning your game shape/stamina changed by a few sublevels, but not a whole level. Similarly, when you are training young players and they don't pop on Friday, it doesn't mean the training is wasted - the sublevel of their skills increased, but it hasn't hit a higher level yet. Speaking of stamina - it works in a similar manner, your player probably dropped a few sublevels in stamina, but didn't drop a "full" level.