The combine is pretty essential for ages and heights. The relative value for an 18 year old is much higher than a 19 year old, such that I do not forsee ranking any 19 year old ahead of the crop of 18 year olds. Until they give 19 year olds comparable stats to a trained 18 year old, this should be the case.
I do not see the initial ball ratings as very accurate - just used in the absence of any other information. I like the new system, but I do not know if I am going to invest any more $$ unless they actually upgraded the pool of draft talent.