Being 16 and 18 or 19 are completely different. He might even grow a little taller in the next couple of seasons. His times are not going to just freeze at 16. Barring any unforseen injury, I expect him to keep progressing as crazy as that sounds. Cooper is in absolutely uncharted territory, as the world has never seen any 800 runner this good, this young. Comparing his situation through the lens of Mo Aman isn't a good starting place because even Mo still improved after 16. If he stays fairly healthy the next few years, there is no way he has peaked yet. That's just not how healthy 16 year olds develop on average. In fact, should he somehow make it to the worlds final in the next few weeks, as bonkers as it sounds, he might run a 1:41 before this season is over. Being that 1:42 was his first reaction to being in a race with true world class competition, he might have another second or god knows how low drop in him right now.