Sometimes it is a front/back thing. You can look at some old programs and see that all fronts were assigned numbers 10-39 and all backs were numbers 40 and higher. Ocala did this some years as an example. Also...the sizes matter. A smaller fronton will order the shirts (in various sizes)...and then assign them to the players. So if you wear an XL then your number will have to be one that came in XL size. If 25 is a size M then that won't be your number. Typically this is done at places where the roster changes a lot from year to year. Often times the shirts need to be ordered before the roster is even final....if they are ordering new ones for season. But same thing on the old inventory. If the fronton has number 55 jersey open...and you want that number....well then hopefully that is your size. Because they don't have a 55 in S,M,L,XL. They have it in one size.