The Belgian striker left the Blues to join Everton in a £28m move in 2014, and it appears that he will be joining the West London club for the second time in his career.
"If you're Abramovich, you would be asking questions," he said on ESPN FC.
"You buy the guy, you loan him out two seasons on the trot and then you sell him for, what, £28million something like that?
"And then you buy him back for £80million?
"I think if I'm Abramovich I'm saying 'hold on a minute what's going on here?'"
"Lukaku for me doesn't fit into a team that predominantly spends most of the time in and around the opposition's box, he's a guy that needs space in my opinion," he added.
"If you look at Chelsea last year, one of the things I loved watching was Costa and (Eden) Hazard together, playing little one twos and playing with each other in a small space.
"Lukaku can't do that so if they do get Lukaku, that would change a lot for me the way Chelsea attack."