You get a feeling that it’s a really case of what might’ve been for Ryan Jack at Rangers. The former Aberdeen captain is one of the club’s longest-serving players, having joined Rangers back in 2017, coincidentally the first transfer window of Pedro Caixinha’s ill-fated Ibrox reign. But it wasn’t until Steven Gerrard came into Ibrox a year later that the Scotland international midfielder’s game was taken to the next level. There was a moment when Rangers looked to have finally found their midfield marshal, Ryan Jack a clever, industrious midfielder with an eye for goal. But since that rapid de…