The point being, England will have a multitude of staff. Coaches, fitness gurus, dieticians etc. They all contribute to the comeraderie of the team not just Southgate. So I think you are being over generous in your assumption "he's brought the squad together". You just have to look at the Newcastle backroom staff. Southgates job as you say are team selection, tactics and formations of which he is extremely average and that's me being kind.