We say 'attacker', because at the moment, Nkunku isn't being recognised as a natural goalscorer by Enzo Maresca, his Chelsea manager. Even his hat-trick against Barrow in the Carabao Cup wasn't enough to convince Maresca that Nkunku deserves equal-footing with Nicolas Jackson when it comes to competing for the No9 position in his system.
"Christo probably is the one that every time he plays, he scores and he did well," says the Italian. "Also, probably was our best player in pre-season, no doubt. He was playing as an attacking midfielder and now we are using him as a No9.
"We all know he is not a No9, it's more second striker, behind the striker, between the lines."
As we say, for his manager, Nkunku isn't a natural No9. That's even if he performs as he has in the very same position. And it's a situation that now has the 26 year-old's camp sending out feelers to Paris - and PSG's transfers chief, Luis Campos.
Of course, it broke in England earlier this week that Manchester United had made enquiries. With Jean-Claude Blanc now part of the brainstrust at United and given the links with Ligue 1 partners, Nice... it does make sense that the first big signing of the Ruben Amorim era could be French-connected.
But in Paris, where these stories of Nkunku being unsettled have originated, it's PSG who are making all the running. And it's movement that is being encouraged from the player's end.
Ten goals in 17 goals this season - after last term's injury woes - makes good reading for Nkunku. Three in four in Europe. The hat-trick in the Cup. But that's just it, the opportunities that he's been granted this season. Opportunities that he's taken with both hands. They've all been in the secondary competitions. It's understood days after his reps and PSG intermediaries touched base, Nkunku was left non-plussed when entering the pitch on 88 minutes for Sunday's 1-1 draw with Arsenal. He's kept up his end of the bargain, but when it comes to the games that matter, Nkunku is regarded strictly as a reserve.
And it's a situation that's left him fed-up. It can't be a coincidence that less than 24 hours after that limited cameo, we had the French press talking up Nkunku's frustration and the prospect of a return home to Lagny-sur-Marne. A day later and it was the English press and United registering their interest. Something is brewing. And it's going to force Chelsea into a decision.
"He checks a lot of the boxes," one PSG source says. "He suits our new project: he's French, he developed in Paris, has a collective mindset, is versatile and still young."
After Kylian Mbappe's departure for Real Madrid, PSG are moving away from the Galacticos approach to a more team-oriented transfer policy. Approved by president Nasser Al-Khelaifi. And driven by Campos. Bringing back Nkunku after five years away would suit this new way of team-building.
And as we say, Nkunku has been receptive. Those close to the forward insist 'Christo' "wants to have fun again; to be playing regularly" and "to find himself in a familiar environment" again. It really does sound like if PSG can bring Chelsea to the table, Nkunku will be happy to push things along at his end.
But that's the question: should Chelsea encourage it? As Maresca states, the Frenchman was their best performer in preseason. And when he gets on the pitch, Nkunku has almost always delivered. For a board with the ambitions of Chelsea - that is, to get themselves back to matching the feats of the Abramovich era - you need players like Nkunku.
Indeed, for this column, we'd put the Frenchman well ahead of Mykhaylo Mudryk, Pedro Neto, Jadon Sancho and Noni Madueke in any type of pecking order. But it does appear Maresca has other ideas.
"With the amount of players we have, they are versatile and we can use Christo as a nine, Christo in the pocket," Maresca has also stated this season.
"He doesn't like to be used wide, he prefers to be inside - we know that. But sometimes for balance, sometimes they have to play in positions that are not the best for them.
"But the important thing is they adapt and try to be their best."
Ten goals in 17 appearances does suggest Nkunku is trying his best. But for the moment, that doesn't appear enough for his manager. And it's a test for Maresca. He has a potential world-beater on his hands. A player capable of walking into most teams across Europe. And while it can be argued Maresca's team selection has worked so far this season, it is still the manager's job to keep talent like Nkunku happy and involved.
The news out of Paris this week suggests Nkunku isn't convinced. And it's an issue for Maresca to solve. If Chelsea are to be competing for the Premier League and Champions League, they need deep squads with players of the quality of Nkunku.
But with PSG now calling - and the player clearly unsettled - it's a question for Chelsea: do they encourage an offer or resist?