Kubrat Pulev will school and batter Dereck Chisora

You mean Germany. Pulev is past prime but so is Chisora, probably further past prime and especially as far as this matchup goes. Pulev will still be allowed to clinch, maybe not as much but there will be a lot of it.

 

Kevin Johnson is probably Chisora's 3rd best win and probably Pulev's 7th.

Pulev is not "stepping up" against 12 loss journeyman Chisora; he's stepping down against a guy he schooled years ago. Chisora is a shell of the fighter he was when he lost to Pulev. Even Hughie Fury would batter this version of Chisora.

 

Pulev is on a higher level than Chisora so "stepping up" is relative. If Pulev had fought Parker twice, Whyte twice, Helenius and Kabayel, he would have been "stepping down" and favoured to win those fights. Pulev would have more losses if he'd faced Fury, Vitali, Usyk and the rest but it would be several more, not ten more.

Hughie was 24 when he fought Pulev and the inactive 37 year old Pulev won the vast majority of the rounds, beat Hughie far better than Parker did a greener, less mature version. Chisora is Pulev's best win as he at least beat Takam in a fight he was getting battered in and Pulev beat Chisora by a wide margin, stylistically it was an easy fight. The likes of ancient Tony Thompson, prime Dimitrenko and prime Ustinov would be top wins on Chisora's record. Even Jerry Forrest would be one of Chisora's top 5 wins.

 

To get the title shot against Wlad he had some notable victories at the time: Pulev was 20-0, with victories over 32-1 Dimitrenko (whose only loss was an MD against contender Eddie Chambers) by KO11, 27-0 Ustinov by KO11 and a clear UD over 38-3 2x world title challenger Tony Thompson, who was coming off back to back KO victories over the heavily hyped, formerly 15-0 prospect/contender David Price. Pulev was regarded as one of Wlad's strongest contenders.

To get his second title shot against AJ he went on an 8 win streak, with notable victories over world title challengers 25-5 Chisora and 21-1 Hughie, both by clear UD's. He only had one loss (to Wlad) and the likes of Whyte and Miller weren't interested in fighting him in Bulgaria, even at 37 after an 18 month layoff. I don't see how he was gifted title shots relative to other contenders around the same time.

I imagine he doesn't want to risk getting his brains bashed in by a prospect/rising contender in a small money fight in the twilight of his career.

 

"Bogdan Dinu and Rydell Booker since the AJ fight"

They were also pre-AJ opponents. The only opponents he's fought since AJ are a washed up mma fighter in a hybrid bout and Forrest on Triller.

"On the basis of fighting George Arias..."

You neglected to acknowledge beating Chisora prior to being named mandatory, plus the fact that Whyte and Miller (and no doubt others) avoided him.

"And then he gets injured before his fight with AJ"

That was suspect.

"Somehow Pulev finally does get to fight AJ...without much in the way of meaningful victories"

On his post-Wlad 8 fight win streak Chisora and Hughie were notable wins. There were more dangerous contenders AJ's team could have gone for (Ortiz in 2017, Usyk in 2020) but it's not Pulev's fault he was chosen instead of them. Compare Pulev's record to the records of other AJ contenders and it doesn't compare unfavourably to most, all of them have their filler opponents and tune-ups.

I think the main reason why boxing fans don't like Pulev is his cautious jab and grab style and lack of KO power.