I've been reading LOA 12, LOA 13, and the CBA. I've been trying to make a case for both sides (I've already decided for myself for personal reasons). I'm trying to be objective and factual.
Basically, grey and poor language notwithstanding,
LOA 12 allows the commercial agreement (NEA) and schedule coordination. It adds some protections specific to the relief given in 1.F.1 and 1.F.3. Basically, it allows codesharing for the purpose of network feed. The NEA can be accomplished to an extent with the relief/within the confines of LOA 12.
LOA 13 allows for focus city to focus city flying on AA/AE. Allows up to 35% of Caribbean flying on AA code. It further allows up to 100% of international flying (Caribbean excluded) to have AA code. (Specifically, all of this from BOS, EWR, JFK and LGA only). There are protections within the relief, specifically related to growth metrics which are basically summarized best by saying "we can't shrink while under the NEA".

In return for all of this, we get slots at LGA, JFK and EWR we otherwise would likely never have access to. This provides avenues for growth (long term). In the short term, it provides us slots to feed AA's network where we can replace 50 seat CRJs with more ASM and a better product. What part of the slots, the most coveted part in all of this as I understand it, can't we get with just LOA 12?

Finally, reading through LOA 13, one finds deliberately written non-concrete language. A few examples:
The MEC, through emails and podcast, have done a strong job assuring the union that the NEA agreement can/WILL be cancelled by the MEC if the growth metrics/restrictions they have placed are not met. Yet, they added this line in B.3.a., "unless the Association consents to renewal of the JB-AA Commercial Agreement." Why would they add that? We could have a much different MEC in five years. The company could miss ALL the metrics, yet come to us with a sob story about how they are going to make them this time, and it was only due to COVID-22 they didn't. That line needs to be deleted.

Or how about B.4.d., "Consent shall not be unreasonably withheld." That is to "material changes" to the entire agreement. How did the company convince them to put that in there? What's the definition of "unreasonable"? How will that hold in front of an arbitrator when JB is trying to grow yet it only hurts pilots?

That's it for now.
Fire away. Missing anything??