So I fly AA a lot because of Oneworld basically so I'm familiar with their faults.

If this is recent however it's not entirely their fault. AA is a big customer for the 737 MAX. That plane's grounding has hit their schedule pretty hard. Most of those flights involved Miami for some reason but to backfill those routes they've taken planes off existing routes that weren't fully utilized. Like I'm fairly sure some weekend JFK-SEA flights were canceled and my guess was to free up an old 737 for some other route.

They're also the largest airline in the world I believe so i can't even begin to imagine the complexity of the logistics of this like making sure you have a flight crew in the right place as well as all the other changes to services like maintaining the plane, cleaning it after a flight, baggage handling, stocking the plane with food and drinks and so on.

If your changes in itinerary were less recent than that then my next question is does this involve regional flights? I fly between hubs mostly so I haven't had that experience.

American has 24 Boeing 737-MAX8 planes out of a fleet of 963. For comparison, Southwest, who also has a large fleet of planes, has 34 out of 754.

Effectively they are operating a fleet that is 2.5% smaller than normal. I expect some impact to their schedule, but it shouldn't hit it that hard.

2.5% may seem small but I'd wager the ripple is larger than you think. I have read upwards of 90 regularly scheduled flights being canceled well into June. Assume each flight has an average of 150 passengers (plane capacity is between 138-230) then you are looking at 13,500 lost connections every day, seven days a week well into high time for travel. I am hard pressed to believe that sacrifices will not be made on account of this seemingly minimal fleet size change.

Huh, ok, that seems fair. I was wondering if the 737 max was involved, but didn't realize the ripple effects were that big. I've had schedule changes from them in the last month or so all up and down the NE corridor mostly.