AA is a simple man and a below average GM, but really, it's not fair to blame him for this specific season going wrong. This team should have won almost 90 games. Yes, depth was an issue, and that's his fault, but that doesn't account for anything close to a ~20 game swing.
Too many players underperformed their projections and/or got hurt. That's it. I don't think it's really intellectually honest to try and construct some post-facto reason for why it all happened.
Morrow: Expected 2-3.5. Got -0.1.
Johnson: Expected same as Morrow. Got 0.5.
Dickey: Expected 4-6. Got 2.4.
Reyes: Expected 4+. Got 2.
Lawrie: 2.5+. Got 1.2.
Bonifacio: Expected 1. Got -0.4.
Arencibia: Probably 1 worse than expected.
Melky: At least 3 wins worse than expected.
Maicer: ~3 wins worse than expected.
That's up to 21.7 lost wins right there.
Colby overperformed by probably 3, and Lind by almost 2. So let's say they lost about 16-17 wins through random performance fluctuations and poor luck. That turns a ~90 win team into a 74 win team.
It really is a wonderful, beautiful turn of karmic justice after all of the bad process.... but it's not AA's fault.
He still sucks though.