I got a really useful 19yr old Draftee this year (
(14839656)). I've sold him for a very nice price (Thanks Fluisterwoud!!) to a team who could really use him well. I also used him pretty well and he got pretty good Ratings during his matches.
I know all of us want to get a SUPERDUPER 18 year old draftee. A+ Grade, 5-ball Potential. But I'll settle for a guy like this every draft. Maybe not 5-ball potential, but I don't need that until I'm in Div 1. My best player at this time in my Div III season is a guy who has 6th man potential. He's maxed out, but very very useful.
So, my opinion is that 19yr old draftees are no problem to me.
Having the 19yr olds have a bit more experience or skills than 18yr olds is logical though.