Southpaw_dad:
Not only is seperation important, but you need to know very specifically who you are measured against. A Lefty pitcher gets a little break on the velocity, but it also depends on his body type. If he is long and lanky and "projects" then he will get an additional break over a shorter kid. It may not be fair, but it is life.
My son tried out for the Area Code team and his coach told him before he he went that he would be compared with big strong corner guys because of his height, and although he is not slow, he did not have CF speed (as compared to who was there) A 6'4" 210lb kid is going to get a break over a 6'3" 170 lb kid when it comes to a corner position. Taller pitchers got a little break on velocity, but if you had a shorter stature you had better be in the 90's some of the taller one's were working high 80's.
If you have not done it yet get to an elite event and see what kind of talent that it is out there, it is pretty amazing. Like PG said there are kids that have "it" along with aptitiude.
Get out there and work hard as there are some really amazing ball players playing HS ball right now.