I think of the Gandolfini/Figgis story. The only way Gandolfini could have done that to Mike Figgis was if Gandolfini was Tony Soprano... and he was. He had already proven that. That was excellent casting. Mess up Tony, the center does not hold. Directors become almost superfluous.
This is true, but in many ways, directing for episodic television is in general superfluous. It's not at all the same as directing a film.