nobody seems to be factoring in a Seal isn't a dude off the street who decided one day to become a Seal and trained for 21 months of whatever the program is to become one. I bet a lot have past training, maybe in some of the same discipline MMA fighters do. Weather it be BJJ, Kick Boxing, Wrestling, whatever. Seals are bad ass before becoming Seals, you cannot just decided you want to be one. If the typical ATOT, or typical human woke up one day wanting to be a Seal, they would fail out before the first day of boot camp was over.
Hell week they have to go all week non stop with only 4 hours of sleep total over 5 days. Seals have a mentality that would make them hard to beat in a fight. You can't really use a GSP as a good gauge for MMA Vs. Seal, GSP is elite even amongst MMA fighters. The typical MMA fighter against a Seal would be a great fight. And I bet some Seals could stand and bang with the upper level MMA dudes.