Long hopes that Lukaku can return to the Hawthorns for a second season on loan as part of his development.
He said: "Rom is still young. You look at him and I can't believe he is 19-20.
"He has a lot of learning to do but he wants to learn, is relishing the challenge here and it is good to play alongside him.
"He is a nuisance up front, he is a big strong lad.
"They've got plenty of options at Chelsea and I think he likes it here. He likes playing for the manager. He likes the lads, he finds it fun coming to training every day and he seems happy here.
"Hopefully we can get him back next season and keep him going the way he is going."