He is not an outright Key Position player, agreed. But the manner in which he plays is very much as a lead-up marking target who is also strong enough to win contested marking battles.
i.e. the comparison to Tom Lynch who is the exact same height and is their 4th 'tall' if you like. He has the speed and good hands to be the hit up target but is also agile enough to be pretty good when it hits the deck.
Lav is an exciting prospect because like you say, he is clean with his ball handling (no puns please lol) and has speed.
You can say he is 'seen' as a midfielder but the fact is if he is coming into the AFL side this year he will be playing as a forward not as a midfielder.
I hope next year and into the future he can develop into a mid/fwd.