In a sport where an athlete's peak is generally only a few years, what you're talking about (and wrongly holding against Aldo) is actually just the the normal divisional turn over rate and it happens in all divisions, especially in ones that had long reigning champs -- for example, None of the guys Max beat did well against volk, none of the guys anderson silva beat did particularly well against future Middle weight champs, none of the guys Usman beat have done well (or are likely to do well) against Leon and other future WW champs etc etc etc.
Aldo's best wins were happening from 2009-2014. Aldo, as the champ, was facing and beating his opponents while they were at their absolute peak, whereas Max and volk fought aldo's left over opponents, often years later, as they were down sliding out of the peak of their careers. It makes sense that none of those guys Aldo beat would do well in the twilight of their careers against newer, fresher blood. That is the normal turn over that happens in this sport.