His middle-ness is precisely what works with him. That’s a guy who can negotiate, not afraid to let the other guy look good.
This is what I liked about him with Obama. This is what they liked about him in 1986 (see link above and read it).
He’s NOT shiny and exciting. But he knows what he’s doing.
He will make Kamala Harris shine. She doesn’t need his help either. Obama did not need his help. But he helped Obama shine. That kind of role *is* uncommonly put in charge due to lack of shininess but they are good leaders.