Most fullbacks can't defend in this era of high line football, fullbacks are 70% attacking 30% defending, the likes of Cancelo, Hakimi , Alexander play like midfielder winger hybrids who bomb forward and come inside linking play. The days of pure defending FBs play for teams who never win anything and are from a bygone age, the game has evolved to a faster more goals more chance creation, hence the age of the attacking full back., Shows how Cafu and Carlos were ahead of their time ,they wouldn't look out of place in today's football two decades later.