Willie,
regardless of what you hear, the majority of candidates that miss out are culled (for want of better words) at the QF Psych & Skills (Stage 1). If you miss that, unfortunately you proceed no further.
Of those that progress to Stage 2, approx 60-80%, (depending on the day) get through the sim ride. Sometimes less, sometimes more. The remainder that are scrubbed blow the interview.
In summary, you must pass the QF Psych and Skills to get to Stage 2. (This has the largest failure rate).
You must pass both the Sim and Interview to get a guernsey. A fail in either may get you called back in a few months to repeat the part that you were weak in, if you were particularly outstanding in the part you passed.
The person you write about would still have had to successfully complete all the steps above, irrespective of how they were selected......