The Fir Park manager likens the unassuming 20-year-old Irishman to a 7m-rated prospect once in his charge; is "excited" over Sheridan's "potential", and has no doubts whatsoever that he is a "future Celtic player" and has all the attributes to earn full Republic of Ireland honours. As he became resigned to losing Chris Porter, McGhee admits he "kept mentioning" to friend Gordon Strachan about the possibility of acquiring the player on a short-term deal, Yet he was still "a little bit surprised to get him" on the final day of the January transfer window. He wasn't alone.
Great swathes of the Celtic supporters remain uncomfortable with losing a forward whose strike-rate for their side this season is bettered only by Scott McDonald. The struggles of Jan Vennegoor of Hesselink and Georgios Samaras to rediscover their scoring touch have hardly quelled such unease. Indeed, Sheridan and McDonald are the only Celtic strikers to find the net in the past six weeks.
No matter that the youngster's goal came in Motherwell colours last weekend. As he was netting the winner for his temporary team in Inverness, at Celtic Park his permanent employers were trouncing St Mirren 7-0 without any frontline performer getting in on the scoring act. A quirk inevitably lost on no-one, it was the cue for more brow-furrowing from the club's followers at the player being let loose in Lanarkshire. For while the 6ft 2in Gaelic-footballer-of-not-so-very-long-ago might be raw as sugar beet, that did not prevent him refining for four vital goals during his spell deputising for injured senior Celtic colleagues across the winter months of 2008.
"Just after the St Mirren game somebody told me no strikers scored, which was a surprise, but winning 7-0 they can't really complain," says the quietly-spoken Sheridan. "It's nice to hear some Celtic supporters still want me there, but it's only now I've gone away that the fans are maybe looking for reasons because strikers haven't scored. I could have stayed, been playing and not scoring as well."
Chances are, however, he would not have been playing much right now if still at Celtic. McGhee believes his buddy performed a balancing act in responding to his coaxing. If Strachan had retained Sheridan he would have been "no further forward by the end of the season". Sending him out to get "a run of 20 games" at Motherwell means the Irish under-21 internationalist could return to Celtic Park as "a serious contender".
The chance to play regularly meant for Sheridan it "wasn't really a difficult decision" to agree to a brief change of scene. He doesn't see it as a pause in his Celtic career so much as the opportunity to fast forward. "Some might look at it as a backward step, but if you are playing every week rather than sitting on the bench you are going to benefit," he says. "The manager told me to go out and relax and enjoy playing. With Celtic every game it crucial. There is pressure to win here too, but it's different."
Sheridan's story is a whole heap different from the footballing norm. It is small wonder he recalls the run of games that brought him a start against Manchester United for the Champions League visit to Glasgow in November as "surreal". Bred and seemingly genetically predisposed to play Gaelic, his current profession has only been a real consuming concern since he was 15.
Effectively he has missed years of junior schooling in what he checks himself for calling "soccer". Only when travelling down to Dublin to play for Belvedere FC five years ago did he "decide to prioritise" football. Not, however, before he was offered the opportunity to play Australian rules with Brisbane Lions. "That came at a time when I started getting trials at football clubs," he says. "It could have gone pear-shaped."
Instead the ball remained round. Celtic were the only club to offer him a contract and have been rewarded with usefulness at an age that defied all expectations. Sheridan may have been thrown in to the first team because he was Strachan's only fit target man. But he then remained involved on merit – testament to his ability to short-cut the development process. Owing to serious injury problems in previous years, he has hardly played for the reserves. He may be 20, but he accepts Strachan's assertion that in game time he is a footballing 18-year-old. "It will take me a year, maybe more, to get more awareness," says the affable youngster.
McGhee is convinced he can help hone a fellow striker with "that bit about him". He possesses stature, pace, an ability to hang in the air and can "naturally skelp" the ball, as he did netting with an almighty crashing effort at Inverness last week. What he does not yet possess is the maturity and menace to bring all these facets together.
"He is a wee bit naive, the way he runs around, but when he starts to channel it I think he could be a really good player," the Fir Park manager says. "He has to become a number nine. He is too big, too mobile and too good to pair off with someone. He has to do more in the gym to get more physical, all round. At the moment he's a bit floppy, but by 23 he'll be a totally different shape."
Sheridan knows enough about Scottish football's ways to recognise "it was for the best" that he wasn't allowed to play against his own team the other week. The opportunity to play against Rangers presents altogether different possibilities. "I could yet have some say in the title," the player offers. He has already had more say in it than he or anyone else could have envisaged.
CELTIC'S STRIKERS: HIT OR MISS?
Played: 23 (+ 1 sub). Goals: 12. Strike rate: 1 in 2 games
Played: 14 (+ 10 sub). Goals: 12. Strike rate: 1 in 2 games
Played: 9 (+ 5 sub). Goals: 5. Strike rate: 1 in 2.8 games
JAN VENNEGOOR OF HESSELINK
Played: 10 (+ 5 sub). Goals: 2. Strike rate: 1 in 7.5 games