There is a loss, but they still get some. I don't know what balls require but I believe there's only like a 25% loss of B1 during the freezing process.
According to United States Department of Agriculture (2010), “The freezing process itself does not destroy nutrients. In meat and poultry products, there is little change in nutrient value during freezer storage” (Nutrient Retention, para. 8).
Well there are studies that exist that focus on thiamine. I'm sure google will bring them up since I have looked into this before during another debate about canned foods vs frozen.