i also strongly disagree , the bb's have already stated that there is only one hidden skill known as physical skill - which controls player aggressiveness - which effects the likely hood of him fouling players - players fouling him - getting or giving out injuries.
the difference in def you are probably noticing most likely comes from the different levels of help defense in given teams , a sensational defender will get more help from help defense then a wonderous defender , this could make the lower defender seem better.
it is also rumored there is sub levels of game shape so while the 2 defenders may look to be in the same level of game shape the lower defender may of in fact been higher.
there is far to much information to come to such a statement .