There is plenty of research that you can do on what soccer jersey numbers mean but
one thing you will find is that when a young person first starts out playing, they will generally pick a number that means something to them. This will be because they have a favorite player or perhaps the number means something significant to them. Sometimes they may get lucky enough to be able to have that number when they turn professional and other times they may just have to go with what they are given. Either way, when you are given a number it can become very significant to the player and stick with them.