Think it is necessary to at least have that someone with very good/great positional sense. For example, Bastian was brilliant in both roles. As for Dzajic/Matthews, both were traditional wingers where their duty was first and foremost to attack. It is quite clear the tactics were different and they were not so tasked with the defensive duties. But from what I saw, both would be capable of providing acceptable/solid defensive cover if being asked. Still, there is no doubt that physio team's workrate is superior.