Haye didn't look much taller next to Vitali in those old TV interviews. Haye maybe half an inch taller than Adamek, if anything.
Vitali-Adamek is a bigger fight than Haye-Wlad. Vitali has the strongest claim to be the true heavyweight champion. Haye and Wlad are flat-track bullies.
Adamek is like a small version of Vitali. Not particularly fast but he uses decent boxing skills to keep touching his opponent. Vitali is a bigger more powerful fighter. Vitali will win but Vitali has slowed down now and he is suspect to a small guy who can keep touching him. Adamek should look for the speed, co-ordination, agility advantage and he has been preparing for this fight physically, mentally and strategically for a while.