I get your point about Kelly also in relation to genuine speed in the open, but feel you are missing his sharp footwork and I think for a youngster, he offers plenty of potential.I understand where you are coming from .
The fact is players can learn tackling techniques and improve on their defence in their 20's but as far as blistering speed goes , if they don't have it by then they will never have it .
In actual fact Bozo - I reckon if you give him a go, you will be on the Kelly train mid 2018 season