The issue is, Iowa recruits a lot of guys who need time to develop and grow. We tend to recruit a lot of 6'5 280 LB guards who might not have the best physique for that weight, who need a couple years in the S/C program to get up into the 290's 300's and then if you have a guy who is used to playing in pass-heavy offenses in high school, they don't do a lot of firing off the ball and playing with leverage, they don't know/understand zone blocking concepts. aren't used to combo blocking, reaching to the next level, etc. A CB at iowa has zone responsibility (mostly) and probably doesn't have to put in 20+ lbs of good weight to be ready early.