I’m sure he does, but while game reps are severely limited, practice reps are the answer. His hands aren’t doing what
they need to do when his mind is getting distracted in game.
You can practice teaching your hands to function without thinking about it in two ways:
1) through similar distraction (and practicing focus)
2) through boredom.
Catching hundreds of passes whilst bored and tired after practice has a very similar effect in training your unfocused/distracted mind to still make catches.
He should practice as much as he can in stressful situations and with distraction, but it’s much easier to get 100+ bored catches per day after practice.
Lots of great receivers do this (eg. St. Brown, Rice, etc.)