Far better diplomat than general. But Marshall wisely saw that was what the job of SCAEF required. Besides navigating prickly personalities like Churchill (soft underbelly, indeed) and de Gaulle, he managed the infighting among his generals. Maybe he learned about how to deal with that type of overarching ego during his time on MacArthur’s staff. He made his share of mistakes but in the end it’s hard to see how anyone else could have done better.
I’m always amazed at how Eisenhower balanced Churchill, DeGaulle, Patton and Montgomery during the war.