Back in March at my AA interview one of the hiring captains mentioned AA had 15k applications, of which half were qualified. Not sure what he meant by qualified, but he made it sound like half had some sort of negative discriminator and are not being looked at (whether it was DUIs, no degree, multiple checkride failures, did not meet company hiring mins in some way I do not know), leaving the other half of the guys/gals on the list.
Also of note is that AA says they do not have a pilot hiring shortage, ie the 7-8k applications on file, but there is a regional pilot shortage.