I wonder if the CPU isn't redshirting players at the beginning of the year, but when they're buried on the depth chart and not getting playing time, they are automatically redshirted at the end the season.
I took over a CPU team in a OD and was surprised to find that the CPU hadn't redshirted anyone and I had 7 QBs. But 5 of them will end up being redshirted because they aren't going to play a snap this year.