The sim and the aircraft are different places, different environments. Just last year we had a low-time First Officer emerge from simultaor training without difficulty (his first airline job, turboprop). Struggled through a fair-weather week of IOE. Began flying the line, and upon the commencement of his first instrument approach procedure with people in the back, simply froze up. Crossed his hands, looked out the window, stopped moving, stopped talking, stopped listening. Wouldn't respond to the captain, wouldn't say a word. He just let the captain fly the procedure, configure the aircraft, and run the radios all by his lonesome.
Once safely on terra firma, he packed up his stuff and walked away without a word. Needless to say, he was terminated, and he didn't even protest. My point: The simulator does not always separate the men from the boys.