The evidence and stats are starting to suggest he could indeed be.
The 21-year-old is certainly filling the Greek enigma's shooting boots when the Hoops hit the road.
McGregor scored in Reykjavik. He scored in Warsaw. He scored in Perth.
And he is hoping to keep this remarkable road show rolling along in Maribor tonight when Celtic face NK in the first leg of their Champions League play-off tie.
You would have got long odds against the kid just back from a season on loan at Notts County being the Hoops' top scorer at this stage of the campaign.
But that's where McGregor currently stands, with a goal every second game - literally.
He has not been able to do it either at Murrayfield or Celtic Park, though he did hit come close when he hit a post early in the 6-1 rout of Dundee United at the weekend.
McGregor gave notice of what he could bring to the side when he scored with his first touch when coming on as sub in the opening pre-season game against Krasnador in Austria.
His consistent form since then is the real bonus as youngsters are notorious for seeing spikes and troughs in their performances as they find their feet in the big boys' playground.
But McGregor is no overnight sensation. In fact, he first popped up on the Hoops radar when selected to sit on the bench in the Europa League game against Rennes in France three years ago - the night Celtic took their first steps on the road to redemption in European competition after struggling for a couple of years.
Ronny Deila has taken over where Neil Lennon left off in marking McGregor down as a kid with a real chance, trusting the grounded wide midfielder enough to start in every game this season.
McGregor has already shown why Notts County were desperate to keep him as he banged in 14 goals in the league during his loan, why Wolves tried for months to sign him - and why Celtic kept them all at arm's length.
Now, despite having been at the club since he was nine, Deila considers McGregor one of his new signings - and a very important one.
The man who places the very highest demands on his players, young and old, is quick to compare McGregor to another wide player who burst onto the scene and stayed there - James Forrest.
"I think Callum is quite similar to Jamesie, some of the techniques he has," said the manager who is grateful that, with Forrest once again absent through injury, he has McGregor fit and ready to take the game to Maribor tonight.
"The goals from Callum are a big plus for us," continued Deila.
"He is a like a new player - but there is much more to come from him."
If the next instalment can be delivered tonight in Slovenia, the timing would be perfect.
With Scott Brown, Forrest, Adam Matthews and new Bhoy Aleksander Tonev all ruled out with injury, while Efe Ambrose is serving the second game in the two-match ban handed to him for his red card in Warsaw, the manager's quest to find a settled side is facing several obstacles.
The new players introduced in the past few weeks - Craig Gordon, Jo Inge Berget, Jason Denayer and Tonev - have integrated with different levels of success so far.
Gordon, Denayar and Berget are expected to feature in Maribor, where an away goal and at least a draw will be the target.
It appears to be a stage set perfectly for McGregor to grab another leading role - and another goal.
It might appear to be a heavy burden of expectation to place on a youngster who, a few weeks ago, was considered by most fans to be getting little more than a taste of first-team football before being sent back down to continue his education in the development squad.
But McGregor already looks settled in his new environment, and has impressed another player who managed to make the step up at an early age and show an old head on young shoulders.
From his position as full- back behind McGregor, Matthews has seen first-hand what the new Bhoy can bring to the side.
The Welsh international has been wowed by his skills and eye for goal, but also by his temperament.
"Callum doesn't say much and keeps himself to himself," explained Matthews, a player who himself merges into the background in the dressing room before coming to the fore on the field.
"Nothing seems to faze him, and I think that helps.
"In the games he has played he has not looked nervous, and he wants to get on the ball and has done really well."
MATTHEWS - who will have to settle for watching McGregor from afar tonight as he remained in Glasgow to receive treatment for the calf injury which flared up during the warm-up for Saturday's game - knows from personal experience how tough it it to carry pre-season promise into competitive action.
But it has been a seamless transition for McGregor and the defender said: "Callum has done brilliantly.
"He has probably been our most consistent and best player.
"He showed last season for Notts County what a good player he is. And, when he trained with us, he showed he can play at this level.
"I think he has gone from strength to strength, and is playing with a lot of confidence."
It's an attribute which will be an essential part of his armoury if McGregor is to make it four from four on the road when he trains his sights on Maribor tonight.