The fact that Alcaraz ended the season on such poor form makes me wonder if it is just a slump, due to fatigue from a long season, or if players are starting to figure out Alcaraz. Post-US Open, Alcaraz was losing matches to players he would routinely beat. Losses to the likes of Djokovic and Sinner are fine, but losing to players like Dimitrov and Safiullin is a bit concerning.
It's going to be interesting to see whether Alcaraz can recapture his pre-US Open form, but one thing is for certain: It's not just going to be Alcaraz going forward. Sinner is there. Rune is there. Shelton might be already there, but even if you don't think so, he's definitely coming.
In my opinion, Carlos's less-than-impressive 2nd half of the year is about Carlos, not about players "figuring" it out. It's not like his game is based a parlor trick. I think it's about the pressure, a post-Wimbledon sink because he's young and getting used to all of this. There's a lot of distraction potential in there. His timing has been off. If you got to watch the Alcaraz d. Medvedev match the other day, Medvedev is a really smart guy, so if everyone's figured Alcaraz out, then why not Meddie? Because, as
@Kieran suggests, Carlos "outbefungled"™ him. To me, the issue was not the field, but Charly.
I fully think that Sinner, Rune and Alcaraz could make up a future big 3, and as I've said, I'm in favor of Shelton being in there, I admire your championing of him, but I think it's a bit early. But I did quote Nick Kyrgios above for you, because he puts Shelton, Fils and Tiafoe as potentials in there.