[drcy]

Not always, but can be. Same with MLB authentication.

MLB only authenticates stuff as they directly witness for themselves with their own eyes (Saw the player take the jersey off his back, as opposed to found it in a pile in the lockerroom after the game). Thus, if a jersey is authenticated as team issued it may have been game worn. And I know of numersous cases where a photo-identified game-worn jersey got the team issued COA. But many team issued jerseys were just team issued and not used.

You will need other evidence-- wear/usage, photo id, other.