Rangers were preparing for the Scottish Championship season in the summer of 2015.
Rewind back to the summer of 2015, and Rangers are preparing to mount a promotion charge on the Scottish Championship with Mark Warburton in charge at Ibrox. Of course, they would go on to win the title - 11 points clear.
Before the season had started, Celtic and Rangers had locked horns over the signing of then-Hibernian playmaker Allan after an excellent 2014-15 campaign with Hibs that saw him provide 17 assists in 40 matches.
But Stubbs, who was in charge of Hibs and looking to rival Rangers for the 15-16 title, prevented a move to Ibrox for the boyhood Rangers fan as they were direct rivals:
"We all know Scotty’s choice would have been to go to Rangers. I think he is a fan and we all also know the reasons we couldn’t sell him to Rangers at the time. And then Scotty and his advisors chose Celtic," Stubbs told the Herald in 2017.
Interestingly, Allan reacted to his dream Rangers move being binned by joining bitter Old Firm rivals Celtic. Fast forward three years, and he will be wishing Hibs allowed him to move to Ibrox.
Indeed, in three years, Allan has managed just 17 appearances for Celtic and has been shipped out on loan to the likes of Rotherham United, Dundee and then back to Easter Road last season.
Allan failed to secure another loan for the 2018-19 campaign, and now at 26 years of age, the midfielder finds himself on the Celtic scrapheap under Brendan Rodgers after being left out of their Europa League squad.
To make matters worse, he has less than 12 months remaining on his contract. A departure seems inevitable, as does any game time. He is yet to make an appearance this season for the Hoops.
A move to Rangers, then, three years ago would have proved a much better career transfer for Allan, rather than Celtic.