A humble guy willing to give everything is a great start. I remember when mourinho was mentioning how he managed big players like ronalda, Drogba lampard and such. But that he also managed player with not great talent but great attitude for work and such. It was more like if he was talking about his players at inter. And truly he didn't have great players like that of real Madrid quality but some of them gave themselves completely to the cause at inter. It is no surprise to me why for mourinho azpilicueta has become one of his go to guys. Because despite not being as amazing as Cole, his attitude and work rate is immense. I don't know nothing about salah but I do know that if he comes with that humbleness and desire to give everything for the team no matter where he plays, he will also become a go to player for mourinho.