Speaking on The Football Show on Sky Sports, Fjortoft said: "What he's done is they've always chosen the places he can develop as a player.
"Then he went to Dortmund because it was the right place for him now.
"He will go to the Premier League I think eventually but it will take him time. It went quicker for him at Salzburg than he thought but he's at a good place now.
"I can't see him moving short-term but he will end up in the Premier League."
Fjortoft added: "His family background overall is playing a big part. He's a good lad. Alf-Inge has been good at talking about developing the player and looking around for people who could help him out.
"When they took Raiola on he helped find an excuse for him not to go to Manchester. I think Alf-Inge has been good so he's now thinking how he can improve. He was a tough guy on the pitch and he's got that into Erling as well.
"He is playing a major part for him and the team they've built around him are local people from Norway."