So far Fleck has lost 11 of 50 recruits for an attrition rate of 22%. This is a few years old, but a quick eyeball test says the average in the P5 would be around 40%. Minnesota's was 42% the last time the data was update from 2002 - 2014.
https://www.reddit.com/r/CFB/comments/2y4waq/power_5_conference_attrition_rates_for_2002/
Fleck's attrition rate will likely climb over the next few years, closer to 40%. If he continues to sign 25 players per class, and keeps 60% of them, that's ~16 per class. 16 x 5 = 80 of the 85 scholarships.
Just based on the average attrition and a little math, they can continue to take 25 per class and the numbers will naturally work out. With redshirts they can also get to the point where they are losing 20-25 upperclassmen and signing 25 freshman.