Ok a quick explenation on the whole "power level" thing since it appears that people get annoyed by it without any real reason.
This isnÂ´t the first time Oda used an indicator to determine a strenght rank among the villains. In fact, this is the third time. The only difference to the other two times is that it is a new kind of indicator. To prove that letÂ´s elaborate the other two times.
In the Baroque Works arc, the strenght level of the villains was determined by the numbers that they received for their codenames. The lower the number the higher the rank was. This didnÂ´t mean that it had something to do with strenght alone (Mr. 3 and Mr. 4 are the best example).
This was a criminal organisation so such an order made sense.
In Skypiea we had the four priests. Their indicators were their ordeals with the 0%, 2%, 10% and 50% probability of survival. Another indicator to determine a rank among them and it made sense to use such an indicator because it was priests of god. A Mr 1,2,3 ranking wouldnÂ´t work that good in such a context.
Now to get to the current arc. Why does such a ranking make sense here? Because except for Spandam all the others are Rokushiki users, which means they are all trained in close combat.
Now if anybody of you is familiar with the boxing sport then youÂ´ll know that boxers often measure the speed of their punches to deternmine how strong it is. That really happens. However the strongest or fastest punch doesnÂ´t determine the better boxer. But it is an indicator on ranking the punching strenght of the boxers themselves. And in real life boxers would also freak out like Jabura if somebody has a stronger punch. They would say something like "yeah heÂ´s got the stronger punch but IÂ´m the better boxer and I can knock him out."
So since the CP9ers are all trained fighters this ranking system makes sense here, just like the ordeal survival probabilities made sense for priests and the agent names made sense for a criminal organisation.
This is definitely not the first time that Oda used a ranking system in One Piece so I donÂ´t get why everybody freaks out. IÂ´m sure that we wonÂ´t see it again in the next mega arc.