Rangers know all about hanging on to players for too long and not maximising their transfer fees. In fact, the Gers have had so many high profile players walk out the door for nothing in the last two seasons that they can pretty much be considered experts. In amongst the world’s most tragic player trading models – a system that exists at Ibrox in name only – Filip Helander, Ryan Kent, Alfredo Morelos, John Lundstram, Borna Barisic, Kemar Roofe and Ryan Jack have all left the club without recouping Rangers so much as a penny. So when other clubs take a different approach – especially those who …