As far as I have been able to make out of the hexagon, it is merely a help to show approximate strenghts in general areas.
Power holds (I believe): Shot Power, Balance. Basically, it is an estimate how powerful the player is, whether it is putting power behind a shot, or being able to stand up in a duel.
Speed might not only have Top Speed and Acceleration, but also Dribble Speed, passing speed, long pass speed, and such.
Technique will probably have Technique, aswell as Shot Technique and perhaps also dribble accuracy.
In order to know for sure, you could simply create a player with 99 for all stats, then drop them down to 0 individually and for each check which part of the hexagon is affected, and perhaps also by what amount (assuming certain parameters are weighted differently depending on how relevant the parameter is for the hexagon area it affects).