Ok i think the point is not getting through at all. Lets take Pellistri out of this equation, lets compare Antony to a winger. He does none of the things that are needed for a right winger to support the striker.
1. He very rarely crosses and if he does it's usually relayed via telegraph for the defenders to be ready for it
2. He very rarely takes his man on and complete the move. He either cuts back or tries to come inside and shot or does tricks and passes back
3. He very rarely makes runs behind the defender.
4. He stops all forward momentum by taking more touches than needed
He does track back and has a good engine so i will give him that. He has a good left foot that gets us a goal once in every 8 games or so. Not good enough. It was his first season and i will give him benefit of the doubt and hoping for him to improve.
I get what your saying but even in your points its not that straight forward:
1) He played without a proper striker for pretty much all of last season. If you go back to his last season at Ajax he was doing exactly what you wanted from him. Even still whether you have a left footed or right footed winger it comes down to team instructions on whether EtH wants Antony crossing or shooting more. The whole point of having a left footed rw is so they can both cross and shoot. Either way the point is moot as Pellistri very likely puts in less balls than Antony. The only one who has proved at a high level that they can consistently deliver balls to a striker is Antony.
2) That I agree with and he looks like he is working on it, but replacing him with a winger who is equally as bad but doesn't provide all the other things Antony does isnt the answer.
3) This may be team instructions, after all Antony is the one consistent attacker who shows for the ball under pressure. Even then running behind is not something Pellistri has shown is a strength of his.
4) This is inconsistent decision making on his part which hopefully he will improve. However as above very often he is one of the few players able to drag the team up the pitch.
Now I'm not saying a right footed winger would not be useful in this team, I'm just saying a winger as poor as Pellistri is is not useful to this team over playing Antony.