The pro-shop operator has told me I'm pretty much his only customer that has this issue, and that it has to be a problem with me screwing in the IT too hard or too tight. I am about 99% sure that this isn't the issue though because it would make sense that my most used balls would break more often than the ones I use less often. My Arch Rival has over 300 gamers on it, my C System Maxxed Out is over 150 games, and I have a Revolver with over 150 games as well, and all of those are still on the original system.
The thumb always seems to be flush with the ball, and like I said, up until last year I had never had a single issue with these. I thought maybe they changed something in their process or made them slightly differently from the factory and for some reason I was one of the few people affected. Then I realized it always happens to the same ball. I've tried plugging it entirely and installing a new one, but it still has the same issue from time to time. So aside from the situation I described above, I'm not really sure what else it could be.
I really don't want to use another system, the local shop here doesn't have switch grips in stock, I might be able to get him to order them for me, but I wasn't sure if he'd need special drill bits or other tools.