Normally contracts are signed with two different suppliers to provide the championship items. The contracts are very specific as to the number of items needed at the end of the game and the number of items needed to be completed throughout the near future. The company with the winning team makes out. (but it is a ton of work). The company with the losing team takes a small bath. All preprinted or embroidered items, screens, digital files, or copies of the losing team items must be destroyed at the end of the game. There are a small amount of items pre printed or embroidered, but they are closely watched until either the winning team gets to wear them or they are destroyed. With most hats for either the SuperBowl or the World Series the design is generic enough that they can pre embroider the logos and then the specific winning team logo is heat applied to the center of the logo. That way they can sell right away while the market is hot. It is a gamble to bid on the hot market of championship apparel. If you make out it is a long week of 24 hour days to flood the market with the items. If you lose it is a long week of shipping back all the inks, shirt blanks, thread and hats to all the suppliers. Very rarely does any of the items get out of the hands of the sanctioning organization.
If you ever see one it is rare.