When it comes to the full-back positions, Celtic haven't exactly brought in great quality with the Hoops devoid of many first-class options in Ange Postecoglou's ranks at Parkhead.
Take Boli Bolingoli for example. The Belgian full-back was the subject of a rather stern telling off from Neil Lennon when the current pandemic was at its peak.
He visited Spain on an unsanctioned trip, failed to isolate when he came home and as a result, put the entirety of Celtic's playing and coaching staff at huge risk of the virus.
But then there's Greg Taylor as well, someone who is rather divisive in Glasgow.
Capable of bursting forward from full-back and delivering a cross, he is arguably the closest thing the Bhoys have had to Kieran Tierney since he departed for Arsenal.
Yet, met with inconsistency and injuries, he's hardly an ideal long-term heir.
Of course, Josip Juranovic has deputised ably in that position at times since Postecoglou signed him but they didn't half make a messy situation out of one of their former academy gems, someone who would now be their first choice every week.
That happens to be Aaron Hickey, a player who Celtic let go in his mid-teens to Hearts and then failed to bring back to Paradise in two successive summers.
The Hoops have long been linked with a move to bring him back into the fold but after a £1.5m sale to Serie A side Bologna, his path now looks destined for greater things.
The 19-year-old has been labelled an "exceptional talent" by Daniel Stendel and has even been compared to Sergio Busquets due to his ability to feature in a holding midfield role too.
Yet, it's on the left-hand side of defence, an area that needs obvious improvement long-term at Celtic, that he's become a star in.
As a teenager, he has quickly become one of the most promising young defenders in Italy, scoring four times and assisting a strike in 2021/22 so far.
Furthermore, he ranks in the top 1% of full-backs across Europe's top five leagues over the last year for shot on-target percentage, and in the same 1% for fouls drawn by an opponent per 90 minutes.
With those stats in mind, it would appear that not only did Celtic lose a tricky defender from their academy, but they have also missed a golden chance to bring him back to Glasgow.
Sadly, any chance of luring him back has now gone as well, with Transfermarkt valuing the Scot at a whopping £11.7m, an increase of 766% on what he was sold for and surely miles out of Postecoglou's price range.
It's fair to say they will have plenty of regrets about Hickey.