Yes, he is, and it's not a slight on Casey, but Chesley is just that good.
Casey is more of a project. He's got elite skills, but you can tell he's a guy that played both forward and defense before the NTDP. He's also a 1st round caliber prospect, but he plays a less complete game right now.
Chesley has all the tools and plays a complete game. He's good defensively, he's physical, very good skater, high IQ, good offense, etc. Stylistically he reminds me a lot of McAvoy / Doughty and I think he has the same upside as them as well. He's a much better U17 player than McAvoy, but Charlie's development curve during his U18-20 seasons was phenomenal.
Chesley checks all the boxes of an elite #1 defense prospect.