Gauthier is 19, big players tend to take longer to develop b/c one reason they're big is a growth spurt in their teens, and it can take a little time to develop body control. Beware of the big man who is polished at a young age, less upside (worse case was Phillies giving $4M to 15 year old Ortiz b/c he was literally a man among boys, now he's a man among better men).
He's had a good freshman year in college, on a team with limited talent. He's still learning to play center, but to complain that he was put at LW with Cooley at center is kinda silly.
How good of a center will he be? His playmaking seemed to improve in college, but he's probably never going to excel there. The key will be his defensive play - a big fast center who understands defense can be a dominant two way player.
If his defense doesn't develop, his future will be as a sniper at LW, and his shot is good enough for 30 goal potential (the reason the Flyers focused on snipers is b/c good defensive teams limit "dirty" goals, and the Flyers have lacked top shooters).