Did you see Matthews?
Tom was so helping Dexter!
My theory is this, that as captain, Mathews made sure that Dexter was always the smartest man in the room.
Quinn, Angel and Masuka?
Tom made it so easy for Dexter over the years that he doesn't know how to compete on a level playing field.
LaGuerta isn't supposed to be his sort of threat because Dexter put her through a crucible and her psyche profile has changed from when Matthews tagged her as mostly harmless.