Did you know that Real Madrid legend Raul spent his formative years in the academy of bitter rivals Atletico, only to be released when president Jesus Gil decided to close Los Colchoneros’ youth system to save a bit of dough?
Ryan Giggs, meanwhile, had a spell in the blue of Manchester City, PSG allowed Matteo Guendouzi to leave while Bayern Munich discarded Emre Can after barely giving him a look in.
Clearly, every club makes mistakes, and it is not always easy to see which of your fresh-faced youngsters is destined for the top.
So with the January transfer window rolling around, maybe Celtic should attempt to make things right by re-signing these three academy graduates who they are surely kicking themselves about letting go.
Celtic have been scouring the market for a right-back capable of replacing the veteran Mikael Lustig but have already missed out on the likes of Conner Roberts and Cristiano Piccini. So maybe the answer is closer to home – and a player the Scottish champions know well.
O’Donnell has been in terrific form for Kilmarnock this season after all, helping Steve Clarke’s side establish themselves near the top of the table while earning six caps for the Scottish national team too.
Let go by Celtic in 2011, O’Donnell now looks like a ready-made replacement for Lustig in Brendan Rodgers’ starting XI.
Celtic’s defence has given Rodgers no end of headaches across 2018 and the problem is unlikely to go away once the New Year celebrations die down with the future of Dedryck Boyata still up in the air.
The Hoops must start planning for life without the out-of-contract Belgian and Findlay certainly appears to have the talent and potential to fill the void once he bids farewell to life at Parkhead - though comparisons with a certain Jack Hendry are somewhat inevitable.
The 23-year-old failed to make a single appearance for Celtic between 2013 and 2016 and, like O’Donnell, is now going from strength to strength at Killie. Findlay even rubbed salt into the wounds when he scored a winner against The Hoops at Rugby Park earlier this season.
Players move around quickly in the lower leagues of English football but not Carey. The 29-year-old has been Plymouth Argyle’s talisman since he moved to Home Park in 2015 and has seven assists to his name already this season.
Blessed with a wand of a left foot and superb technical quality, Carey has looked far too good for England’s third tier for a while now and perhaps deserves a chance to prove that he’s now at the level Celtic demand.
Unfortunately for the former Republic of Ireland U21 star, Carey turns 30 in May so his chance at the top level might have passed him by.
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