Let me put this another way. Even if the training department were run by a bunch of clowns and you got the complete shaft, in an interview setting it is always better to just admit fault and what you learned from it without making any excuses.

Some training departments are run horribly. The seat fillers may be failed checkride/upgrades themselves, and it sounds like you may have got stuck with a few. You can get sim instructors who just don't care, can't teach (i.e. never flight instructed), and are just in it for the extra pay and little work.

You could have had a combination or all of these factors work against you here. But even if it did, in your next interview just admit fault and don't make any excuses. The airlines eat that **** up. It saves them from any liability if students are forced to admit fault, and it also means they don't have to work as hard to improve their training departments.