They're probably being hyped as they get domestic success. But as soon as they fight a solid foreign boxer, the hype ends.
To be fair Yarde fought admirably vs Kovalev, Beterbiev, who are two of the best Light Heavyweights in recent memory. Also no one favoured him in those fights either so I don't think he was that hyped. Chisora has always been seen as a gatekeeper hes never been over hyped. Whyte was never over hyped his limitations when he stepped up to the next level were very apparent. Joyce, Joshua, I agree were definitely overhyped more so Joyce though. He went from being considered a slow plodder, to the next coming of Foreman and being able to beat a prime Tyson just because he beat Joseph Parker.
I don't know where he goes from this. He only managed to win a world title through VERY careful matchmaking and favorable reffing.
Perhaps pre-Fury 1, Chisora was favoured to win there. Besides that Chisora has been consistently underrated. He significantly overperformed relative to expectations vs Helenius, Vitali, Scott, Whyte 1, Takam, Usyk, Parker 1 and Pulev 2. The others were probably more overhyped than not. Dubois and Joshua go without saying, though Joshua's had far more success than the others. Joyce was underrated pre-Dubois, post-Dubois he was overrated. Whyte was overrated post-Joshua. Yarde was somewhat overrated given he's 1-3 in real fights, including a loss against Arthur.
Okolie is missing a trick here for sure. With some media training he could be the best boxing villain in a long, long time. People would pay good money to shout obscenities at him if he would have the good grace to play the role.