low experience; captain 42 years old and 4500hrs? not much flying per year. I had that much time in my first 5 years and was only 25. the F/O...16,000 hours...hmmm...a 16,000 hour F/O..why was HE not a Captain? Seniority? perhaps, perhaps he was a weak pilot and could not upgrade.
Please get your facts right...
Yes the captain in the left seat had 4500 hrs but considering some pilots start flying these types and even bigger types with less than 300 hrs what can you expect.
Now the co-pilot was really a captain, so really a co-captain with close to 7000 hrs. He was called on one of his days "OFF" to replace the assigned co-pilot who could not fly that day (according to a post on here).
The third pilot sitting in the jump seat was a check pilot, check airman or whatever you want to call him and he's the one with 16,000 hrs.
Why that check pilot was onboard is unknown at this time.