I would presume that there are three stages perhaps of "Professional" game issue/model gloves under the current system of glove manufacturers. Most of the professional gloves are made as "Pro Stock" that is premium gloves, leather and craftsmanship that are ready to provide the professional/major league players. These are pulled out of stock for the individual players who
are under contract and are requesting their "game" gloves from their manufacturer. Most of these are probably distributed during early spring training to the various players, major and minor leaguers. Virtually all of these, with some exceptions, are now made offshore. I am curious, at this point, about the personal embroidery name done on the gloves for specific players, wondering when this is done when the glove is made or afterwards.
Doc can probably answer this question.
Now we have the "game" gloves, issued to players that are returned for some reason and either slightly used (for warmup/catch) or unused by that player. These could also be given to various friends, etc.
The third is most important and valuable glove, is that used in games by the player.
Hope this makes a little sense and it's a little conjecture on my part.