Speaking after South Africa's 18-12 win in the second Lipovitan D Rugby Championship win over the All Blacks, Erasmus credited former All Blacks and now Springbok back coach Tony Brown's contribution in reaching that understanding.
Erasmus said the Springboks respected the All Blacks.
"Tony gave us a perspective on the All Blacks, which told us a lot about the things we didn't understand. We understand it better, and it makes us play better.
"We always respected them, but now we have a better understanding of how they think, from the haka to their individual players and the make-up of their team, and how they do things.
"It's quite amazing what he told us."
While achieving four consecutive wins against the All Blacks had South African fans crowing, Erasmus was more cautious.
"It's important to understand that, for us, four wins is something that's nice to have, but also they have beaten us six times in a row, in games that we were part of, and scored 57 [at Albany] and 40 in Durban against us. There's nothing to brag about; they've done worse for us.
"It feels good that we can pip a team like this again, like last weekend [the first Test]. The way they had played, if they had won, nobody could say they didn't deserve it."
Erasmus said that while South Africa had four wins in a row, the All Blacks still had many records to brag about.
One area the All Blacks did win in Cape Town was at the breakdown.
"Where they beat us was the breakdown, that's where we came totally second best. They definitely overshadowed us."
Captain Siya Kolisi said, "We don't play Super Rugby any more, so it's always special to play against them; that's been going on for over a hundred years now.
"We have so much respect for them, and it's mutual respect between the two teams. We go flat out against each other on the field, then afterwards we can have a beer together."