I agree with a lot of this but I don't think Parker has given up his title aspirations I expect a very intense, motivated Parker this time. And if he loses it really might be time to retire
He fought better fighters who made him look as average as he actually was, as opposed to fighting poor fighters that flattered him greatly.
Parker's movement never offered a path to victory against Wilder. Fury and Ortiz didn't win on points over 5 fights and Parker barely outpointed Takam and Ruiz, failed to outpoint Joshua and Whyte, gifted the win vs Chisora 1. His only chance vs Wilder is a KO, likely early and this is more attainable due to Wilder's age and wear. Barry likely doesn't want Lee to upstage him as a trainer and he would have sent Parker in pointfighting as he did vs AJ.
Couple of things. - he lost his motivation and ambition peaking early and got lazy - he didn't really have that grit in him to truly excel against the odds (not saying he didn't have heart but that he lacked that... nastiness) - he stayed with Kevin Barry too long and learned bad habits that had him overreliant on his athleticism which is now waning A lot of the above has been brewing for a long time and was a reason I jumped off being a fan of his, despite still liking and rooting for him to succeed. But he had so much potential and wasted it staying with a limited trainer too long and lacking the desire to truly prove himself. And now he just comes into fights way too heavy and flat footed, and looks to have lost his handspeed which used to be blistering and even more explosive than Ruiz's. For all of Wilder's faults he always puts in maximum effort in the gym from the looks of it, and always plays to his strengths. I wish I could say the same of Parker.
He fought too safe against joshie and in hindsight could have maybe pulled off a ruiz against him if he'd exchanged. Back then people didn't realise joshie was a bully quitter, they thought he was a lion because he got up after Wald dropped him. Looked like they were happy to get the money fight and play it conservatively and lose on points. Seems like he got fatter and fatter over the years. He was already fat against Hughie. That's not going to help his movement. Fury probably told him to get to 270, where he'd feel strong and not weak and skinny.
I don't think Parker has fallen off. From 2016-2018 his form was beat Takam, Ruiz and Hughie narrowly on points while losing against Joshua and Whyte. If you barely beat Takam and lose to Whyte, you can lose to Chisora and Joyce. He lacked confidence and ambition against Joshua and was bullied by Whyte 5 years ago, he at least dominated Chisora in the rematch and threw a lot of big shots at Joyce before he was ground down late.
You have a point, also to add, Parker's best KO win may be his recent KO of Simon Kean and his best win (in terms of a convincing performance) may actually be Chisora II. His potential/stock have sure dropped, but his actual level? Not so much. I only worry that his chin isn't the same after the Joyce fight.
The image in my head of that is Parker getting up before he even hit the floor lol. Didn't quite look like that when I watched it back again recently. Great shot from Whyte. Parker comes off as the most intelligent and balanced of the top heavyweights. Boxing is one of the few fields where that isn't usually a positive trait.
I don't think he should have got the nod over Ruiz. Perhaps he was in definition , a paper champion. Fairly capable boxer, with stamina and power issues.
The Kean win reminded me of his win over Dimitrenko, certainly one of his best KO's so that's encouraging. I agree about Chisora 2, he battered Chisora in the rematch. But he still needs to show more killer instinct because he should have stopped Chisora. If he drops Wilder he can't let him off the hook or he won't get a second chance. I don't worry about Parker's chin; 5 or 6 years ago he wasn't confident in his punch resistance against Joshua. It's his willingness to test Wilder's chin, which must be dented, that I worry about.
Early in his career as I was watching him I thought he could be a really good fighter, but as you said I think he peaked or just hit his ceiling and never got to the next level. I look for Wilder to dynamite him.
Joey Parker's strength that got him the world trinket was his movement. He could never crack an egg punching power wise, so his elite movement was enough to beat an at the time under rated fast hands Andy. However, him and his team made the mistake of trying to get him to hit harder. By bulking up and putting weight on. He does not have the same foot movement these days. He has never had the killer instinct and aggression that is part and parcel of any elite champion with longevity. Does the version of Joey Parker who dominated Hughie Fury in one of the dullest fights ever even exist anymore? I doubt the current version of Joey Parker even beats Hughie today. Wilder lands the big right at some stage, Joey isnt hard to find these days.