It's true. Ultimately, I know nothing about their maturity levels, and the team does. Also, I really don't care if a 20 year old is a little immature, so long as they're good on the field and not into anything bad or dangerous. Also also, remember that Micah was available partly because he had rumored maturity issues (which soiled him in the eyes of many fans on this board, including myself).
I guess because the draft is so poor at the top, teams are going to be more willing to take chances with some of these guys. It's a weird one this year.