2013-mid 2014. Maelstrom was still around. Dumbo had been moved and was open. The Fantasyland expansion rolled out. In 2014, Mine Train opened. And personal preference here, but VGF opened.
During our visit in 2011, I was shocked at how dirty Magic Kingdom was - trash all over. It was mostly back to normal cleanliness in the 2013/2014 timeframe.
Starting in mid/late 2014, things seemed to go downhill: the loss of Maelstrom signaling EPCOT's destruction and cementing the mindless insertion of Chapek's synergy stuff, the Poly waterfall's removal, increasing Monorail problems and schedule reductions. DHS closed Backlot. Off Kilter went away and was replaced by... I dunno, does anybody even remember what replaced Off Kilter?
Then in 2016 we saw the Osborne lights go away as well as half of that whole park, making it a total waste of a ticket. Soarin' got a new film which is great and all, but the new film was only enjoyable if you were lucky to sit in roughly 6-12 seats in the theater. And 2016 saw the alligator attack and the subsequent installation of rip-rap and fencing around the lake. To be clear, I'm not arguing against the mitigations put in place, but I don't think anyone can argue the negative effect on the resorts' atmosphere. As we approached 2020, that comic book ride started to trash up Future World's skyline and the rumors (and corroborating concept art) about Spaceship Earth's future reworking became clearer. I also swear that the whole drunkfest atmosphere took over EPCOT during the latter half of that decade, too, probably due to the FB/social media effect.
The only positive things from across WDW during the mid-2014 to 2019 timeframe that I can think of was that the sorcerer's hat was removed and that Trader Sam's opened in 2015.
