Zig Zagged: Peter is competent in some functions of his job and abysmal in others.
Averted: Peter is competent enough for his position, and no evidence to the contrary is presented.
Enforced: "Those wage slaves watching this will love it if the boss is terrible. That way they sympathize with the office workers on this sitcom."
Lampshaded: "How did you get promoted?"
Invoked: When it's realized that Peter is incompetent, he's Kicked Upstairs.
Exploited: All of Peter's underlings ignore their own jobs, knowing he won't do anything to correct them.
Defied: "I know I'm a good salesman, but I don't think I should be leading the sales branch."
Discussed: "The management staff need better training, and not just copies of Who Moved My Cheese. They need to be either promoted from the floor and taking a few calls themselves so they know their employee's jobs as well as their own."
Deconstructed: Peter's incompetence comes back to bite him in the butt when the newest Incompetence, Inc. product fails due to him. His entire office is shut down, costing all the employees there their jobs.
Reconstructed: While there are some heavy losses on his end, Peter's office manages to weather the storm, but he's exposed as an incompetent. He's demoted back to Sales, which is where he wanted to be in the first place.
Played For Laughs: Peter at least has a great sense of humour and tends to appear with someone else goofing around.