One of Jurgen Klopp’s most distinctive tactical ideas at Liverpool was the way he used his full-backs. At their very best, the right and left-back in Klopp’s team were two of the most dangerous players on the pitch. More often than not, this was Trent Alexander-Arnold on the right and Andy Robertson on the left. Between them, the pair have redefined the way full-backs are seen throughout European football. Their legacy will live on far beyond their careers. With all due respect to Robertson, it is Alexander-Arnold who captures the imagination a little more in this respect. The academy graduate…