The problem with his Jett is that he is too smart for that agent. On Jett, you need dumb confidence like demon1, something, aspas etc. Take aggressive peeks, get a kill and go for more. See a gap? take the space without hesitation. Got the ult? Fuck shit up. A lot of the times I see him trying to stay alive and then go one for one at the end. That's not how you get the most value out of jett imo.
I think he needs to go for kills and trust his teammates to close it out. Zach was never a primary jett player and if you watch the comms videos he is very 'to the book' type of player. He always tries to make the correct play so I think this will take a bit of time. But when he gets there he will be the best player itw cz he will have the 'dumb' confidence and also the 'smart' brain to maximize his potential.