First of all, those sack numbers are inflated.
Second, stats don't matter in high school. Never have. A kid can have 4 sacks and go to Alabama or a kid can have 15 and not even get an offer.
He doesn't have an offer because he's undersized. It is what it is. I think he's awesome personally. My buddy is his coach, he co-signs for him as well. However, there's not a premium on 6'2" 210lb Defensive Ends. I had a kid last season who was bigger than Chatfield (6'4" 230, although not as good) and Kool called him "too skinny".
You have a set standard of what you're looking for at DE and Kool's "bare minimum" is likely starts around 6'3" 230+. Any kid that is under that size probably ends up falling on their board. Possibly a late offer type of kid.