Latterly farmed-out on two season-long loan deals, to West Brom and then Everton, the physically impressive striker has proved that he can find the net—but he also frequently lacks the finesse of a top striker.
In ascertaining his future, it is worth looking at how he ended up in the loan cycle that sees the end of many a young player's Chelsea ambitions.
Many have pointed to the lacklustre penalty he took in the UEFA Super Cup, in Prague back in August, as being significant in his season.
Utterly nonchalant and seemingly lacking in any scoring potential, the ball was easily saved.
But the apparently hastily constructed loan deal that took him to Goodison Park days later probably had less to do with that than with matters off-pitch.
Lukaku's frequent public insistence that he wants to be the Blues' No. 1 striker (as reported by Press Association's Matt McGeechan in the Daily Mail), does have slight echoes of another centre-forward who found his future lay elsewhere.
The repeated insistence of Daniel Sturridge that he could do a job as centre-forward, before his move to Liverpool where has he proved more than ably that he was right, shows there are bigger issues here than whether or not someone scores a penalty.
Players who put team before personal gain are highly prized at Chelsea. Part of that is a Mourinho thing—it is probably the strongest message he sends out, practically everywhere he manages.
But it is also ingrained in Chelsea too. Note the demotion from the first team of players such as Alex and Nicolas Anelka, and then Florent Malouda—all, essentially, over a perceived (correctly or not) lack of commitment to the club.
There is another figure who looms large over all of this—Fernando Torres.
Chelsea bought the player for £50m and, whatever the on-pitch reality, there still seems to be a belief at some level within the club that he is a £50m player.
There is therefore more than a little chutzpah in a 20-year-old, who has never scored a goal for the club, insisting he can or should usurp such a figure.
This summer will be a key time for Chelsea's forwards.
Samuel Eto'o, clearly now the No. 1 choice at Stamford Bridge, was only ever brought in as a stopgap move on a one-year deal.
Demba Ba has been on the brink of a move elsewhere for much of the last year.
Then there is Torres—with two seasons left of a five-and-a-half-year deal, will this be the time he finally moves on?
There will be opportunities for strikers to carve out a niche at Chelsea.
But with the Blues being linked with names such as Diego Costa and Edinson Cavani, Lukaku may have to reconsider his immediate ambitions to be first choice if he is to return.
Chelsea will also need back-up strikers. Lukaku's future at the club will largely depend on whether or not he is happy to be one.