Okay just so I can get this straight since this seems to be a common question.
You can raise your skill and "unlock" what there is available of your potential skill be just competing and winning challenges. There is no predetermined number of events or challenges it is awarded when "the game" has determined that you have done enough to improve your skill?
skill training increases stats. When it goes past the yellow line (the skill limiter) it becomes unrealized potential. when you beat the middle boss in each Tiger Challenge hexagon, the limiter moves up 10%, turning any unrealized potential to that point into skill.
As you win challenges and tournaments, your ranking will rise from rookie to pro to champion to legend and so on and so forth. So until you reach the next level, your stats will rise but they will not be effective until you attain the next level.
They call it PMS because "Mad Cow Disease" was already taken.