Do you not understand the difference between Whyte and Parker? It's pretty clear to see why that fight had so much hype behind it.
Whyte is/was a well known and loved British boxer, same with Chisora. You're marketing to a British audience, so it's obviously gonna sell better. Whyte is also ranked way higher than Parker and is on a massive win streak, whereas Parker has suffered two losses to Whyte and AJ, and hasn't beaten anybody of note since. Lastly there's also the hype and promise of an amazing fight that it brought over from the first fight.