Fages starred as Saints prevailed 22-25 over Warrington. The Frenchman set up two tries, made five tackle busts and won the man of the match award in the victory.
“Tonight he’s shown how good he is,” Cunningham said.
“Theo’s just coming of age.”
The 21-year old joined St Helens from Salford at the end of 2015.
“Without singing his praises too much, when we initially signed Theo or when we got the opportunity to sign him, it was on the pretence that he’d be the number 7 for the next 14, 15 years,” Cunningham said.
“If you can afford to keep him. Tonight he’s just shown how good a player he is at such a young age. I think with the right people around him doing the right things the majority of the time, he is somebody who that can take you to the right pieces.”