Obviously I haven't spent any time with Rayner to answer your first question.
But are you just going to ignore the fact that dozens people in the media who have met the kid have touted him as a flight risk?
Are you going to ignore the fact that one of our very own posters teaches at his school and he doesn't have the best reputation?
Are you going to ignore the fact that he runs an 11 beep test which most kids are doing by their mid teens?
Have you watched the interview where he's stoked that the beep test is out of the combine? (doesn't seem like great character to me)
As for the Jake Stringer comparison, yes that is absolutely a bad thing, why would we use pick 1 on a medium forward that can't go through the midfield? Maybe I could understand if we already had the midfield stocked, but we don't, so why would we go for a forward?
I sound like a broken record on the endurance, but I would be astounded if he becomes anything more than a 70:30 Forward. Take any group of teenagers with just average genetics, nothing special, just average and put them in the same environment that all the draftees have been in the last 2-3 years. They'd play/train a minimum of 3 times a week, well over the majority would be getting 11+ beep test results (Mathieson even got 12). I just don't think you understand how bad 11 is. When I was in year PE 11 at school quite a few years ago, I remember noting that every guy in the class ran 11+, many of which didn't even play sport.
I don't care how good he is, I just cannot get over the endurance, its laughably bad, I don't even know how it can be so bad when he would have played so much footy over the years, that just points to a combination of bad genetics and poor work ethic.