OK - trying to get a grasp of where my son is. They are having tryouts now and although my son tore his ACL/MCL in football and is unlikely to play until May - he has been cleared to hit. They measured exit speeds today and he hit 91mph off a tee (metal bat) which seems to be really good from reading the above posts.
For the last 3 months we have been swinging from a seated position and using mostly upper body and working on quick hands - it seems to be working well as he was one of the highest on the team. In the last 2 weeks he was cleared to swing away (as long as he is wearing brace). Looks like working on hands and swing path over the last 3 months has worked out well.